Dr Gunnar Kirchhof (Brisbane - AUS)

Director and Soil Scientist, Think Soils

Senior research Fellow, The University of Queensland

Gunnar Kirchhof

Recent Publications

D Hauswirth, Pham Thi Sen, O Nicetic, F Tivet, LQ Doanh, E Van de Fliert, G Kirchhof, S Boulakia, S Chabierski, O Husson, A Chabanne, J Boyer, P Autfray, P Lienhard, JC Legoupil, ML Stevens, 2012. Conservation agriculture and sustainable upland livelihoods innovations for, with and by farmers to adapt to local and global changes, 3rd International Conference on Conservation Agriculture in Southeast Asia. 10th - 15th December 2012, Hanoi (Vietnam)

Agriculture in whatever age, under whatever natural, economic and social conditions, has to feed the human being. To fulfil this mission, the sector has to overcome continuous and changing challenges to achieve notable developments. The Green Revolution, through developing and introducing high-yielding crop varieties and advanced crop management techniques, saved billions people from starvation. The advent of biotechnology, in its turn, has speed up the agricultural growth to meet food demands of the world's booming population. Continuous demographic pressure and rapid market integration have created necessity to further agricultural developments to meet not only food security, but also the increased demands for nutrition security, food safety, energy, etc., while the global climate change has created needs for capturing synergies between agricultural production and environmental protection. New breakthroughs to trigger the second Green Revolution have therefore become necessary. Thus, it is now the right time for us to consider the means to make "the Double-Green Revolution" to become a reality. Conservation Agriculture (CA) has demonstrated potential to meet this goal through designing and promoting the adoption of environment-sound and climate-resilient agricultural production systems. Increasing interests and efforts have been given to CA research for development in the Southeast Asia during the last 15 years.

Gunnar Kirchhof, Nguyen Hoang Phuong, Trinh Duy Nam, Oleg Nicetic, 2012. Farmer-friendly erosion control measures in maize-based systems of the northern mountainous region of Vietnam , 3rd International Conference on Conservation Agriculture in Southeast Asia. 10th - 15th December 2012, Hanoi (Vietnam)

We evaluated soil erosion rates in farmers’ field to assess when erosion occurs during the maize season and to identify which soil management aspects have the most profound impact on soil erosion reduction. We used a modified profile meter method to monitor erosion in farmers field (Hudson, 1993). Unlike Wischmeier plots, this method has minimum impact on farm operations. In short, this method monitors the drop in soil surface level below fixed reference point. These reference points are steel pegs (pins) inserted in the soil and distance between top of pin and soil surface measured following rainfall event. Our pin method comprised 4 soil pins inserted into the ground to ~40 cm in a 70x100 cm rectangle and we monitored soil surface to pin distance at 8 constant locations within this erosion station. Measurement errors using this method can be large due to slumping of soils after tillage and soil swelling. We compensated for these shortcomings by taking a large number of measurements, monitoring of soil bulk density to account for slumping of soil and assumed shrink-swell was negligible on these 1:1 type clay soils. Although slumping occurred, it happened very quickly after tillage following rainfall and once the maize was sown, slumping was no longer observed; i.e. there was no measurable change in surface bulk density after maize was sown. The research comprised of two phases: (i) collection of baseline date on erosion in farmers field and (ii) to monitor soil erosion in field experiments at two Communes, Na Ot (Son La) and La Nga (Moc Chau). The field trials (ii) was a complete randomized design using 4 blocks. Each plot had two erosion monitoring stations and erosion was measured 8 times during the maize season in Na Ot and 10 times in La Nga. Slopes were ~25º. Other key measurements were rainfall intensities, final maize yields, bulk densities and infiltration rates (i.e. single ring). Following discussion with farmers, treatments were adjusted to what farmers though they may use in future. Cultivation at both sites was done using a hand hoe. At La Nga the treatments were (i) cultivation residue retained plus additional mulch added, (ii) cultivation and residue retained, (iii) minimum cultivation with residue retained and (iv) cultivation with residue retained and rice-bean intercrop, i.e. all treatment had residue retained and no burning took place. The amount of residue from the past crop ranged from 1 to 3 t/ha, the additional residue applied ranged from 3 to 5 t/ha. At Na Ot the treatments were (i) slash and burn, (ii) residue retained and cultivation, (iii) residue retained and mini-terraces and (iv) residue retained and minimum cultivation; i.e. all treatment except treatment (i) had residue retained. Average residue amount left from the last season was 4.3 t/ha with an average groundcover of 83% before land preparation. The difference in residue amounts between the two sites is due to grazing during the dry season. For the benchmark study (phase i), erosion was monitored in farmer fields of 5 villages from End-July to mid-October at 5 different times. These villages were located in different communes in 4 provinces (Mai S?n, Moc Chau, Sin Ho, Tam ???ng). Erosion stations were located within farmers’ fields on slopes between 20º and 30º on slope lengths larger than 100 m. Distribution of the 68 erosion station was uneven between farmers’ fields as it depended on access and farmer support to allow measurement. Average soil loss ranged from 8 to 15 t/ha during that time and there were no significant differences between provinces, communes and farmer fields. We attributed these low erosion rates due the late onset of the monitoring schedule; i.e. maize was well established providing effective erosion protection through reducing raindrop impact. Given obvious visual assessment of erosion, we concluded that most erosion occurs during the early phase of the growing season while the soil is unprotected. During the 2011 maize season average erosion at La Nga was 38 t/ha, with a very large variation from 3 to 95 t/ha, but no significant differences between treatment and it was not possible to differentiate between erosion rates at the start and towards the end of the maize season. We attributed the lack of significant differences to the similarity of treatments where all treatments had residue retained as well as the inherent variability of the erosion method we used. At Na Ot total erosion rates were much higher compared to La Nga and segmental regression of erosion rates showed that there was a significant difference between the start and the end of the maize season. Most erosion occurred until the 7 July 2011 (initial soil loss). The first erosion measurement was done on the 22 April and maize sown on the 11 May. This suggests that a large proportion of soil lost during the initial phase occurs after land preparation and before the maize is planted and aggravated by weeding (Podwojewski et al. 2008). Initial soil loss was 226 t/ha for treatment (i), i.e. slashes and burn. There were no significant differences between the other treatments where residue was maintained and average initial soil loss was 101 t/ha. The difference between residue burnt and residue maintained was significant at the 5% level. The average soil loss rates after the 7 July 2011 was 17 t/ha with a range of 5 – 25 t/ha and no significant differences between treatments. The results of our research showed that most soil erosion occurs within the first 2 months of the cropping season and the main factor in reducing erosion is maintaining ground cover. The importance of this finding is that practice to reduce erosion is to encourage farmers not to burn and to maintain crop residue.

Neal Menzies, Andrew Verrell, Gunnar Kirchhof, 2012, Keynote 5: Can conservation farming practices ensure agricultural ecosystem stability?, 3rd International Conference on Conservation Agriculture in Southeast Asia. 10th - 15th December 2012, Hanoi (Vietnam)

Conservation Agriculture is deemed to be the only sustainable form of agricultural production system. Adoption rates in the Americas and Australia have been extremely high associated with increased and more efficient crop production, but primarily due to the reduction of herbicide cost, mainly Glyphosate, after patents expired and competition for production increased, lowering the cost of Glyphosate. Conservation agriculture is a production system where a key component isherbicide use to replace tillage in the control of weeds. Other equally important components are mechanisation, and residue retention; associated with crop rotation to reduce the likelihood of pest and disease outbreaks. Practitioners of conservation agriculture universally understand that that all components must be applied; partial adoption of the conservation agriculture principles will not be sustainable. In regions where conservation agriculture has been adopted as a system, at present, it is the best management practise for agricultural ecosystem sustainability. However, in many developing countries, practise change for all components of conservation agriculture may not be possible. Herbicide availability and cost is probably a major limiting factor; in particular, in many sub-Saharan counties. The need for agricultural mechanisation at present still limits the adoption in many African and Asian countries. Crop rotation may not fit into traditional production systems and minimum tillage is not possible to implement for root or tuber crops. Similarly, genetically modified cotton production requires tillage for pest control. Soil and climate interactions may also hinder adoption of the minimum tillage component. Some soils, for example heavy self-mulching Vertisols respond very well to the conversion from conventional to zero-tillage and benefits in terms of increased water use efficiency are evident shortly after aggressive tillage operations ended. However, less active soils, in particular hardsetting soils, may not respond rapidly to zero tillage, and it may take several years of zero-tillage practise before soil structure has sufficiently improved for conservation farming to outperform conventional practices. In Australia, profound nutrient stratification (accumulation in the surface soil) also presents a challenge to zero tillage. At present is seems that conservation agriculture is promoted as a ‘must adopt’ as a system where, at present, this may clearly not be possible in some biophysical/socio-economic environments. The change to conservation agriculture needs to be stepwise process where adoptable components are promoted and associated limitations are addressed without short term yield sacrifice. Key indicators for the agro-ecosystem stability of conservation agriculture are soil organic matter build-up and carbon sequestration due to minimum soil disturbance and residue retention and increased water use efficiency. Increases in the soil organic carbon stocks are largely reported on conservation agriculture fields in the Americas. Research in Brazil suggests that organic matter build-up under conservation agriculture can even be greater than under natural ecosystems. Results from the USA suggest that soil organic matter build-up is a major mechanisation for carbon sequestration. On Vertisols in Australia adoption of conservation farming was partly due to the realisation that carbon stock depletion needs to be arrested, and the belief that soil organic matter can be increased in conservation agriculture systems. However, despite soil structural improvement due to adoption of zero-tillage systems, recent data from longditudinal studies shows that carbon stocks have continued to decrease under conservation tillage, though at a lower rate than observed in conventional tillage. For example, on farmers field were conservation agriculture has been practised for over two decades, no increase in soil organic carbon was measured. Unless annual rainfall is above 500 mm, increase in soil organic matter as a consequence of conservation farming practises appear to be negligible. If these values also apply to soils and climates in Africa, large regions of Africa need to be excluded as potential carbon sinks. Minimum tillage systems, once soil structure has improved, even in the absence of organic matter increases, will have increased water use efficiency. This is primarily due to the greater amount of actual available water but not necessarily due to an increase in potential plan available water. The main mechanism for high amounts of plant available water in the soil profile and associated higher water use efficiencies is greater infiltration rates that allow the soil profile to fill out with water. Benefits for crops are obvious but there may be a hidden cost for environmental flows. Higher water use efficiency is synonymous to lower losses in the water balance may well lead to reduced water availability downstream from regions were conservation agriculture is practises. The potential impact on landscape hydrology are largely unknown.

Kirchhof G, So HB, Tuong TP (2011). Puddling: Effect on Soil Physical Properties and Crops. In: Encyclopedia of Agrophysics, Springer Reference, Gli?ski, Jan; Horabik, Józef; Lipiec, Jerzy (Eds.). 1st Edition., 2011, p667-8.

Soil puddling for paddy rice production is the process of working saturated or near-saturated soil into soft structureless mud. Tillage in lowland rice production systems (paddy rice) is synonymous with puddling. Puddling is achieved by cultivating the soil under saturated condition using animal drawn or tractor driven implements. Mechanical breaking and dispersing of soil aggregates destroys the soil structure and forms the puddled zone. Puddling softens the soil and assists manual transplantation of rice seedling, minimizes water use through reduced percolation losses and effective weed control. Over time, soil puddling also creates a compacted layer below the puddled zone which further reduces percolation losses. The least permeable zone is usually found just below the puddled layer where tillage implements created a thin smeared layer. The reduction in permeability is mainly caused by blocking of macropores with fine dispersed particles translocated during puddling process, and the smearing effect of the tillage implements. Although lowland rice does not require saturated conditions to produce high yields, it is traditionally kept under submerged conditions to maximize water supply, mobilize nutrients, and to control weeds, which is generally not possible without puddling. However, preferential flow or bypass flow through macropores, cracks, or large biopores contributes to water losses in paddy systems. This includes water losses though bunds which are not puddled. Water moves laterally into the bunds and then percolates down through the under-bund areas that are not puddled. Despite the benefits of puddling for rice production, there are adverse effects, especially on post-rice crop production. Due to its structureless nature, puddled soils tends to harden and crack upon drying, with the rate and size of crack development depending on the rate of drying, type of clay, and clay content. These characteristics are the main constraint to the establishment and growth of post-rice crops. Irrigation of dried paddy soils can result in excessive losses from bypass flow, while severe cracking can result in root breakage and excessive strength impedes root growth. Although soil puddling reduces the percolation rates, the puddling process itself requires large amounts of water. With increasing water scarcity, alternative tillage methods to reduce water use are needed. Dry tillage prior to flooding can reduce water requirements substantially by filling cracks and disrupting bypass flow pathways. It has become apparent that soils have often been puddled excessively. On clay soils, sufficient reduction in hydraulic conductivities can be achieved with only one pass of the puddling implement, but coarser textured soils may require several passes. Landscapes with very shallow water tables may not need puddling at all, while broad cast planting of pre-germinated seed can save labor without sacrificing yield. In the context of rice and upland crop rotations, minimizing puddling to reduce soil structural degradation will benefit post-rice crops such as legumes or wheat.

Radrizzani AB, Shelton HM, Dalzell AC, Kirchhof G (2011). Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in QueenslandCrop & Pasture Science, 2011, 62, 337–345.

Soil organic carbon (OC) and total nitrogen (TN) accumulation in the top 0–0.15m of leucaena–grass pastures were compared with native pastures and with continuously cropped land. OC and TN levels were highest under long-term leucaena–grass pasture (P 20 years old had negative GHG balances; lower additional topsoil OC accumulation rates compared with native grass pastures failed to offset animal emissions.

Liu Y, Sabboh H, Kirchhof G, Sopade P (2010). In vitro starch digestion and potassium release in sweet potato from Papua New Guinea. International Journal of Food Science and Technology 2010, 45, 1925–1931.

Twenty samples of sweet potato from Papua New Guinea, made up of cultivars 3-mun, Carot kaukau, Wahgi besta, Nillgai, Baiyer kaukau, and 1-mun from three provinces, three farmers, and three locations, were subjected to an in vitro starch digestion procedure. Digestion of starch was studied by glucometry, while potassium release was monitored using electrochemistry. The potassium content of the nondigested samples ranged from 4 to 17 mg g)1 dry solids, while the starch content was from 47 to 80 g per 100 g dry solids and independent of G · E effects. In vitro starch digestibility (2–75 g digested starch per 100 g dry starch) significantly (P

Bah R.A, Kravchuk O., Kirchhof G. (2009). Fitting Performance of Particle-size Distribution Models on Data Derived by Conventional and Laser Diffraction Techniques. Soil Science Society America Journal. 73, 1101-1107

Mathematical description of most classical particle size distribution (PSD) data is often used for estimating soil hydraulic properties. Fast laser diffraction (LD) techniques now provide more detailed PSDs, but deriving a function to characterize the entire range of sizes is a major challenge. The aim of this study was to compare the fitting performance of seven PSD functions with one to four parameters on sieve-pipette and LD data sets of fine-textured soils. The fits were evaluated by the adjusted R2, MSE, and Akaike’s information criterion. The fractal and exponential functions performed poorly while the performance of the Gompertz model increased with clay content for the LD data sets. The Fredlund function provided very good fits with sieve-pipette PSDs but not the corresponding LD data sets, probably due to underestimation of the clay fraction in the latter. The two-parameter lognormal function showed better overall performance and provided very good fits with both sieve-pipette and LD data sets.

Bah R.A., Karvchuk O, Kirchhof G. (2009). Sensitivity of drainage to rainfall, vegetation and soil characteristics. Computers and Electronics in Agriculture, Volume 68, Issue 1, August 2009, Pages 1-8.

Rainfall, vegetation characteristics and soil hydraulic properties influence deep drainage patterns in agricultural landscapes, but more information is required on the variability of their interactions with site conditions. Therefore, the objective of the study was to investigate the impact of the interactions of soil permeability, vegetation rooting depth and growth duration on drainage in 3 sites in northern New South Wales, Australia. Local sensitivity analysis was used on drainage estimated by two biophysical models—WaterMod 3, with a crop growth module, and HYDRUS-1D without a crop growth module. The effect of saturated hydraulic conductivity (Ks), growth duration (GD), rooting depth (RD), annual rainfall, and their interactions on deep drainage was evaluated at 3 sites. Simulations were conducted using 30 years of randomly selected climate data from 115 years historical data. Rainfall variability was similar in all 3 sites, so annual rainfall was the dominant factor dictating drainage in all 30 rainfall years whereas GD was more important than RD after accounting for rainfall and drainage was least sensitive to Ks. The minor impact of RD was ascribed to the soil water content being at the lower extraction limit of crops due to potential evaporation being greater than rainfall in almost all months of the rainfall-year. The importance of GD varied between rainfall-years and sites, and was generally higher at high annual rainfall. We conclude that the level of precision at which model inputs are defined would vary with annual rainfall level. Therefore, GD could be defined on a rough scale in low rainfall zones, whereas more precise definitions are necessary at high rainfall. This would depend on classification of rainfall zones based on reliable rainfall data.

Junge, Deji, Abaidoo, Chikoye, Stahr, Kirchhof, OVERVIEW ABOUT SOIL CONSERVATION TECHNOLOGIES AND THEIR PERCEPTION BY FARMERS IN NIGERIA, IN: Soil fertility in sweet potato-based cropping systems in the highlands of Papua New Guinea, 2009, ACIAR Technical Reports 71, Editor G.Kirchhof, p49-59. (http://www.aciar.gov.au/publication/TR71)

In Nigeria, West Africa, soil degradation has been one of the most critical environmental problems for a long time. Hence, there has been and still is an urgent need to develop effective soil resource management systems that can reverse the trend. Sustaining soil productivity will enhance food security and alleviate poverty. An extensive literature search that started in 2006 has shown that soil conservation has a long tradition, and earlier and present initiatives have resulted in various on-farm and off-farm technologies. As these have rarely been evaluated to establish adoption rates, an assessment study was performed in 2007 to analyse the effectiveness and adoption of past and present soil conservation initiatives. Villages with different types of conservation technologies were visited and farmers in south-west Nigeria were interviewed to obtain information on their experiences. Mulching, cover cropping and contour tillage are likely to be effective on-farm soil conservation measures practised in Nigeria. They are generally adopted by farmers as they are compatible with the existing farming system, and cheap and easy to install and maintain. Education, knowledge on soil conservation, labour availability and membership in organisations have a positive influence on the adoption rate of technologies.

Kirchhof G, (2009) Editor, Soil fertility in sweet potato-based cropping systems in the highlands of Papua New Guinea, ACIAR Technical Reports 71, 126p (http://www.aciar.gov.au/publication/TR71)

High population growth is a problem in most developing countries. Projections for many countries are that the increased demand for food will outstrip the capacity of the land to produce that food. In Papua New Guinea (PNG) the population has doubled since 1966 and the current growth rate is around 2.7%. Despite this high growth rate, the area under agricultural production has remained stable, but land use has intensified. Fallow periods have decreased from several decades to less than one decade. This trend towards more continuous cropping systems is linked to high population densities—as the population increases, the demand for food and cash crops increases. Thus, the need to identify promising management practices to expand both food and cash crops, while sustaining soil fertility, is becoming increasingly important for PNG. This problem is not new: nor is it unique to PNG. Theoretical solutions to the problem of increasing crop productivity while sustaining soil productivity exist, but often they are not applicable to the local agroecological and socioeconomic conditions. For example, use of mineral fertiliser could easily offset production constraints due to depletion of nutrients as a result of continuous cropping, but fertiliser is not accessible for most resource-poor farmers in PNG. Therefore, novel integrated soil-, crop-, nutrient- and water-management practices best suited to local conditions should be developed, pilot tested and transferred to the farmers. Prior to engaging in research to improve or overcome soil constraints, it is imperative to understand current land management systems and the socioeconomic drivers behind these systems. Surveys of farmers play an important role in understanding their current practices and identifying the main constraints to increasing crop productivity. Such information is beneficial in the investigation of management practices that optimise the integrated use of all locally available nutrient sources for sustainable crop production, but have minimal adverse effects on the environment. This report summarises the results from a pilot study on soil fertility management funded by the Australian Centre for International Agricultural Research (ACIAR), and reviews sweetpotato-based cropping systems in the highlands of PNG. It also describes the lessons learnt from survey methodologies used to assess the socioeconomic and biophysical constraints to sweetpotato production in this area. Case studies from similar surveys done in Nigeria and northern New South Wales, Australia, are included as examples.

Kirchhof, Daniells, CHANGING TILLAGE MANAGEMENT PRACTICES AND THEIR IMPACT ON SOIL STRUCTURE PROPERTIES IN NORTH WESTERN NEW SOUTH WALES, AUSTRALIA, IN: Soil fertility in sweet potato-based cropping systems in the highlands of Papua New Guinea, 2009, ACIAR Technical Reports 71, Editor G.Kirchhof p60-69. (http://www.aciar.gov.au/publication/TR71)

A study was conducted in 1998 in north-western New South Wales to assess how changes in tillage practices and farmers’ perceptions of ‘good’ or bad’ paddocks relate to soil structural properties. Forty landholders were visited and interviewed to obtain background information on their current and past management practices, crops and cropping systems used, and what they expect in the future. The majority of the soils were Vertosols (78%), with some Kandosols and a few Chromosols. Conventional tillage was practised on 63% of the fields surveyed. Conservation tillage (minimum or zero-tillage) was only practised on swelling clay soils. On these soils 26% of the fields had been converted from conventional to conservation tillage during the past 3 years, while on 14% of the fields conservation tillage had been practised since they were brought into crop production (3–10 years previously). Saturated hydraulic conductivities on the farmed black Vertosols with a history of conventional tillage were lower than those of the virgin sites, but increased after conversion from conventional to conservation tillage. Fields that were brought into cropping during the last 10 years using conservation tillage only had higher saturated conductivities than the virgin sites. There was little effect of cropping history on saturated hydraulic conductivity on the grey Vertosols. Soil organic carbon on the control sites was always greater than on the corresponding cultivated sites, regardless of whether conventional or conservation tillage was practised. Tillage history did not affect any of the measured soil chemical properties. Platyness of soil structure was a clear indicator for wheel-induced compaction. Platy structure was not shown on any of the swelling clay soils at the never-cultivated sites, and tended to be more frequent on the ‘poor’ sites. This was most pronounced for the grey Vertosols, where 80% of the ‘poor’ and 50% of the ‘good’ sites were platy, and on the black Vertosols, with 42% and 31% respectively. The overall close agreement between platyness and the farmers’ perceptions of ‘good’ and ‘poor’ sites indicated that platyness has an impact on soil productivity and that soil compaction continues to be a limiting factor for crop production. We also concluded that black Vertosols respond better to conservation tillage than grey Vertosols, possibly due to their greater resilience and better ability to self-ameliorate. The absence of conservation tillage adoption on non-swelling clay soils in this region (at the time of the study) may reflect the length of time required before conservation tillage improves soil structure and, ultimately, yield.

Kirchhof, Taraken, Ramakrishna, Ratsch, Igua, BIOPHYISCAL CONSTRAINTS OF SWEET POTATO BASED CROPPING SYSTEMS IN THE PNG HIGHLANDS, IN: Soil fertility in sweet potato-based cropping systems in the highlands of Papua New Guinea, 2009, ACIAR Technical Reports 71, Editor G.Kirchhof p95-109. (http://www.aciar.gov.au/publication/TR71)

Population growth in the Paua New Guinea highlands is among the highest in developing countries. While the 2000 census reported a rate of 3%, more realistic estimates may be closer to 2%. Even if exact rates are unknown, the trend of expanding population will continue and could result in a doubling of the population to around 4 million in just over 3.5 decades. This will place unprecedented pressure on the land resource. However, it is still unclear if the resource-base ‘soil’ is indeed being depleted at a greater rate than it can be restored, given the potentially high productivity of the soils in the region. We surveyed farmers and assessed their gardens to evaluate if soil fertility and associated production of the most important staple food, sweetpotato, is indeed declining as a consequence of increasing land pressure, shortening fallow periods and a number of other factors, including pests and diseases. This survey included 95 farmers in four highlands provinces with an average of three districts in each province. Farmers’ perceptions on soil fertility decline and management options were obtained. They were then asked to show us one garden that had recently been brought back into production after fallow, the ‘new’ fertile garden, and another garden that was about to go into fallow, the ‘old’ run-down garden. Plant and soil samples were collected from these two gardens to quantify changes as a result of cropping over time.

Kirchhof, Taraken, Ratsch, Kapal, Igua, SURVEY METHODOLOGY TO ASSESS SOCIO-ECONOMIC AND BIOPHYSICAL CONSTRAINTS – LESSONS LEARNT IN THE PNG HIGHLANDS, IN: Soil fertility in sweet potato-based cropping systems in the highlands of Papua New Guinea, 2009, ACIAR Technical Reports 71, Editor G.Kirchhof p70-78. (http://www.aciar.gov.au/publication/TR71)

Among developing countries, Papua New Guinea (PNG) has one of the highest population growth rates. As land under cultivation has been stable for decades, the increasing demand for food is placing unprecedented pressure on the land resource under agriculture. An exploratory farmer survey in the highlands of PNG was conducted to assess farming practices in relation to soil productivity decline over time as population increases. The survey comprised farmer interviews as well as the collection of a biophysical dataset, including soil and plant analyses, to underpin farmer perceptions of a potential problem regarding soil fertility. Unlike most farmer surveys, this survey combines socioeconomic data with biophysical measurements. This type of exploratory survey was considered to be necessary to delineate the need for further research intervention. The baseline dataset is also useful to measure post-project impact and adoption, which is often inferred from auxiliary data if baseline data are missing. A main deficiency of the exploratory survey was bias in sample location caused by village access problems and safety concerns. The willingness of farmers, male or female, to participate in the interviews, and sample collection for the biophysical assessment of their gardens, were not problems.

Kravchuk , Wilson, Kirchhof, Statistical methods for a soil fertility management survey analysis in Papua New Guinea, IN: Soil fertility in sweet potato-based cropping systems in the highlands of Papua New Guinea, 2009, ACIAR Technical Reports 71, Editor G.Kirchhof p79-87. (http://www.aciar.gov.au/publication/TR71)

This paper is a short communication about methods used in the analysis of biophysical data from the scoping stage of a soil fertility management survey in Papua New Guinea conducted in September–October 2005 (Australian Centre for International Agricultural Research project SMCN/2005/043). The goal of this communication is to describe and promote the good practice of statistics in application to biophysical surveys. A step-by-step analysis is presented of the difference in sweetpotato yield between newly established gardens and gardens that have been cultivated for a long period. We comment on the strengths and limitations of statistical techniques used in the analysis, and also relate the techniques to the corresponding software procedures (R15, Minitab Inc., Chicago). Although we refer to various general methods, the analysis presented is specific to one particular survey. This paper may be useful for agricultural researchers as a case study of the data analysis of field surveys in research or extension projects.

Liu Y, Sabboh H, Kirchhof G, Sopade PA. (2009). Digestibility of starch and potassium in sweetpotato from Papua New Guinea. Proceedings, 15th Triennial Symposium of the International Society for Tropical Root Crops, 2-6 November 2009, International Potato Centre, Lima, Peru.

Potassium is a major mineral in sweetpotato, and like most root crops, sweetpotato has high starch content. There are many cultivars of sweetpotato with genotype and environmental differences, which influence digestibility and bioavailability. Starch and mineral digestibility in food materials are currently topical because of associated nutritional implications. Time-course in-vitro starch and potassium digestibility of 20 samples of sweetpotato from Papua New Guinea were studied using glucometry and electrochemistry/spectroscopy respectively. The samples were made up of six cultivars (3-mun, Carot kaukau, Wahgi besta, Nillgai, Baiyer kaukau, and 1-mun) planted in three provinces by three farmers in three different locations. The potassium content of the non-digested samples ranged from 4 – 17 mg/g dry solids, while the starch content was from 47 – 80 g per 100g dry solids and essentially independent of cultivars, farmers and locations. In-vitro starch digestibility (2 – 75 g digested starch per 100g dry starch) significantly (p

Ramakrishna, A., Bailey, J.S. & Kirchhof, G. (2009). A preliminary diagnosis and recommendation integrated system (DRIS) model for diagnosing the nutrient status of sweet potato (Ipomoea batatas). Plant and Soil. 316, 107-116.

Critical leaf nutrient concentrations have often been used to diagnose the nutritional causes of crop underperformance. Unfortunately, these diagnostic criteria are not available for mature, tuber-bearing sweet potato plants (the word ‘tuber’ being used to describe a swollen root rather than a swollen stem). The Diagnosis and Recommendation Integrated System (DRIS), however, provides a reliable means of linking leaf nutrient concentrations to the yield of sweet potato tubers, and may be developed for this crop using existing data from regional crop surveys. In the present study, tuber yield and leaf nutrient concentration data from a survey of sweet potato gardens conducted in the Papua New Guinea (PNG) highlands in 2005 were used to establish DRIS N, P, K, and S norms and statistical parameters for sweet potato. Although the database was relatively small, the norms derived for nutrient ratios of key biological significance, i.e. N/S and K/N, were within the expected narrow ranges for higher plants, giving credibility to both the database and the DRIS model. Data from future surveys and field trials may subsequently be used to enlarge the database allowing the refinement of model parameters and hopefully an expansion of diagnostic scope to include other macro and micro-nutrients. As it stands, though, this preliminary DRIS model for sweet potato is possibly the best diagnostic tool currently available for evaluating the N, P, K and S statuses of sweet potato crops in the pacific region.

Wegener, Kirchhof, Wilson, SOCIO-ECONOMIC ANALYSIS OF VILLAGE GARDEN MANAGEMENT IN THE PNG HIGHLANDS, IN: Soil fertility in sweet potato-based cropping systems in the highlands of Papua New Guinea, 2009, ACIAR Technical Reports 71, Editor G.Kirchhof p88-94. (http://www.aciar.gov.au/publication/TR71)

A survey of approximately 100 village gardeners in the Papua New Guinea (PNG) highlands was conducted in 2005 as a preliminary step in setting up an Australian Centre for International Agricultural Research project to improve the nutrition of sweetpotato in the highlands. Sweetpotato is the main staple crop in the PNG highlands, which had a population of around 2 million (or 40% of the country’s population) at the 2000 census, with around 2–3% annual growth. Despite these high growth rates, the area under agricultural production has remained fairly static, resulting in increasing pressure on land resources. Farmers are concerned about yield decline, as sweetpotato yields from fallowed land, or land recently brought back into production as part of the recycling of gardens that occurs in the highlands, tend to be much higher (2–8 t/ha tubers) than yields from old gardens. Despite high apparent nutrient stocks and favourable carbon:nitrogen ratios in the soil, most sweetpotato tissue samples have shown low nutrient levels, in particular of nitrogen, phosphorus, potassium and boron. The survey was conducted to assemble background information on farm locations, farm practices, crop yields, and soil and plant analysis. The conceptual framework proposed to guide the analysis was that background factors (such as location, garden type, land availability, age and sex of farmer, number of children in household and sources of other income) affect management practices. These management practices (soil preparation, planting system, fertility management including fallowing, use of animals such as goats and pigs in the farming system, and crop rotations) influence outcomes such as plant and soil analyses; sweetpotato yields; plant symptoms; tuber characteristics such as weight, size, colour and cracking; presence of nematodes; and ability to grow other crops. A preliminary analysis of the survey data has been conducted and results are reported in this paper.

Bailey, J.S., Ramakrishna A. & Kirchhof, G. (2008). Relationships between important soil variables in moderately acidic (pH = 5.5) soils in the highlands of Papua New Guinea and management implications for subsistence farmers. Soil Use and Management. 24, 281-291.

The fertility of farmed soils in parts of the Papua New Guinea (PNG) highlands reputedly has been declining for some time owing to population pressure. To assess the extent of the problem, a survey of sweet potato gardens was conducted across four of the highlands provinces and information on soil variables was obtained for gardens on soils of volcanic and non-volcanic origins. In the absence of fertilizer application, soil fertility in the humid tropics is largely a function of soil cation exchange capacity (CEC), and soils of low CEC had previously been reported in this region. In the present study, relationships between effective CEC (ECEC) and other soil properties in moderately acidic soils (pH 5.5–6.3) were investigated to see if there was scope for improving soil cation retention characteristics through management of key soil variables. For volcanic soils of varying allophane content, ECEC was, unexpectedly, negatively correlated with soil C and soil C/ N, most probably because of the formation of humus–allophane complexes which had facilitated organic matter accumulation whilst dramatically reducing the free negative charges on the material. Given the latter outcome, the indigenous practice of heaping compost in the centre of soil mounds appeared to be one of the best strategies for circumventing the problem of low CEC, as nutrients in the compost are held in an environment virtually independent of the surrounding soil mineralogy. Although the positive correlation between soil pH and soil ECEC was weak for volcanic soils, it was concluded that liming might nevertheless be an effective means of enhancing the nutrient retention characteristics of these soils provided the practicalities and costs were not prohibitive.

Bailey, J.S., Ramakrishna, A. & Kirchhof, G. (2008). An evaluation of nutritional constraints on sweet potato (Ipomoea batatas) production in the central highlands of Papua New Guinea. Plant and Soil. 316, 97-105.

Sweet potato (Ipomoea batatas) is the staple food crop in the highlands of Papua New Guinea (PNG). Declining crop productivity, however, appears to be threatening the sustainability of sweet potato-based farming systems within the region, a probable cause being the exhaustion of soil nutrient reserves in continuously cultivated sweet potato gardens. To assess the extent of the problem, a survey of sweet potato gardens was conducted across four of the highlands provinces and information on soil and crop variables was obtained for old gardens (cultivated over many seasons) and new gardens (newly brought into cultivation) on soils of volcanic and non-volcanic origin. Crop leaf nutrient data collected in the survey were interpreted using the Diagnosis and Recommendation Integrated System (DRIS), to try to identify the main nutritional constraints on tuber production in different garden types on soils of volcanic or non-nonvolcanic origin. The results suggested that K deficiency was the primary cause of poor crop production in almost a third of sweet potato gardens, but was more of a problem in old gardens than in new. Phosphorus deficiency was also a problem on volcanic soils, and S deficiency on non-volcanic soils. These latter deficiencies, however, were at least as prevalent in new gardens as in old. Important factors contributing to K and S depletion from garden systems were the removal of K and S-rich vines from cultivation areas, the shortening of fallow periods and the burning of weed and crop residues, the latter releasing S (SO2) to the atmosphere. Correction of K and S deficiencies may require the recycling of old vines back to sweet potato cultivation areas and the adoption of a zero-burn policy for fallow management. Correction of P deficiency may necessitate the use of P-accumulating fallow species, e.g. wild Mexican sunflower (Tithonia diversifolia), to extract the P fixed by sesquioxide and allophanic minerals.

Beal CD, Rassam DW, Gardner EA, Kirchhof G, Menzies NW. (2008). Influence of Hydraulic Loading and Effluent Flux on Surface Surcharging in Soil Absorption Systems. Journal of Hydrologic Engineering. 13:8, 681-692.

The goal of this study was to investigate how extreme hydraulic loading influences hydraulic pathways, and thus failure potential, of two soil absorption systems. A grid of tensiometers and piezometers were installed beneath and adjacent to the absorption trenches, and water height was manipulated to simulate different hydraulic loadings. At both sites, measured soil matric potentials along the trench sidewalls increased toward zero as water height increased over time, indicating that water was preferentially flowing laterally above the biomat zones. Saturated hydraulic conductivity Ks of the soil and biomat, and other hydraulic parameters were calibrated using inverse modeling procedures in HYDRUS-2D. We found generally good agreement between measured and predicted matric potentials. The calibrated model was then used to predict fluxes through different infiltrative zones under typical and extreme hydraulic loads. Modeling indicated that the overall infiltration rates through the biomat and subbiomat zones fell within a relatively narrow range of 0.025–0.046 m/day at the two sites. Under extreme hydraulic loading to trenches, fluxes through the upper trench sidewalls i.e., the exfiltration zone were predicted to be substantially greater i.e., 80% of total flux than through the biomat zone. This confirms the conclusions made from field results, that a permeable exfiltration zone provides a critical buffer to surface surcharging during extreme trench loading. Conversely, the presence of a high sidewall biomat can reduce sidewall exfiltration of effluent, and therefore increase the likelihood of surface surcharging.

Kirchhof G, Ramakrishna A (2008). Analysis of biophysical and socio-economic constraints to soil fertility management in the PNG Highlands. Final report – ACIAR project SMCN 2005/043. 37p. http://www.aciar.gov.au/project/SMCN/2005/043

Project Background and Objectives In Papua New Guinea's highlands, soils are rich and productive. Both crop production and agroforestry are widely practiced. The most extensively grown crop is sweet potato, the main food staple, cultivated on between 50 and 90 per cent of arable land. Recent declines in sweet potato yield suggest soil fertility is also declining. Pests and diseases may play a role, as may the shortening of fallow periods to cater for increased cropping to feed a growing population. Understanding the factors contributing to soil fertility and sweet potato yield decline is needed to guide future R&D activities. Information to build this understanding was collected to determine these factors, including the socio-economics of farmer decision-making. Project Outcomes The project team surveyed farmers and assessed their gardens to evaluate if soil fertility and associated production of the most important staple, sweet potato, was indeed declining as a consequence of increasing land pressure, shortening fallow periods and a number of other factors including pests and diseases. This survey included 95 farmers in four Highland provinces with an average of three villages in each province. Farmer's perceptions on soil fertility decline and management options were obtained. They were then asked to show the team one garden which had recently been brought back into production after fallow, the 'new' fertile garden, and another garden which was about to go into fallow, the 'old' run-down garden. Plant and soil samples were collected from these two gardens to quantify changes as a result of cropping over time. Sweet potato yields Sweet potatoes are harvested sequentially, making it notoriously difficult to obtain reliable yield data. The team used single harvest yields to assess relative production from this 'one-off' farmer survey. In both gardens, old and new, single harvest yields of up to 30 t/ha were observed with a median yield of 6 t/ha. Due to the sequential harvesting these yields were considerably lower than the average total yields of 13-15t/ha for lowland and highland systems reported by Bourke and Vlassak (2004). The large variation in the measured yields and cultivars prevented the use of covariates such as number of previous harvests and age of sweet potato plant to estimate total yields. However the team's observations were similar to others (2006) from an EU funded project on early maturing sweet potato varieties in the lowlands executed by NARI. Likely causes for the low yields were nutrient deficiencies, pests and diseases and presence of viruses in the sweet potato planting material (traditional and improved). Nutrient deficiencies were evident even though the predominantly volcanic ash soils in the Highlands are regarded as very fertile soils. In a 1997 study more than 50% of sweet potato tissue samples collected were deficient in N, P, K, S and B. Unclean planting material is also a major contributing factor to low yield, but it is unclear if pathogen-tested varieties would suffer nutrient deficiencies comparable to traditional varieties. Yield trends in old and new gardens Pests and diseases: The cause for low yields in old gardens? There was no difference in the degree of insect infestation of tubers between the old and new gardens (p=13%). There was also no significant difference in the expected percentage of cracked tubers between the old and new gardens (p-value > 7%). But the average yield of vines with cracked tubers was higher in the new gardens, indicating that new gardens produce higher yields even though tubers may have cracks. Despite higher yields, the new gardens tended to have larger counts of nematodes (p=5%), suggesting that the nematodes could be either non-parasitic or infestation is not a critical factor driving yield. The distribution of weevils was significantly different between the old and new gardens. The chances of the presence of weevils or larvae are significantly higher in the old garden (p-value 2200m) showed that high altitudes have considerably higher total N and soil organic carbon (SOC) than the lower. Despite these subtle differences in apparent soil fertility they had no impact on sweet potato yield. This is of particular interest because SOC is often regarded as an important indicator for soil health and fertility. Farmers perception The farmer's response to the survey was a strong willingness to cooperate. Farmers related yield reduction to soil fertility decline and were eager to collaborate as partners and requested feedback from our work. Their observation was that yields in older gardens are lower than in newer gardens and they blamed poor soil conditions for this decline. We asked farmers whether they could grow corn or common bean as a control question to assess their ability to judge soil fertility. The responses to both questions were closely related and farmers thought that the new gardens were more suitable for growing corn or common bean than the old gardens (corn p=4%, bean p=8%). However, the farmer's soil fertility assessment was not related to the sweet potato yields we observed, but it supported the argument that soil fertility differences exist between old and new garden. Soil fertility management and planting systems Yields in the new gardens were not affected by planting systems, but yields in the old gardens were highest if farmers used large mounds. In both, old and new gardens, mounds more than 70 cm high were associated with fertility management such as composting and short fallow (in old gardens). The high mounds system was mostly associated with high altitude. However, the difference in planting systems does not explain all the effect of altitude (p

Kirchhof G, Ramakrishna A (2008). Soil fertility assessment of soils in the highlands of Papua New Guinea. Paper. Soils2008 Conference – Soil, the living skin of planet Earth. Palmerston North, New Zealand, 1 – 5 Dec 2008. http://www.soilsconference.co.nz/page.php?17

The population in PNG highlands has increased on an average at 2.8% during 1980-2000 (National Statistical Office, 2002) and is amongst the highest in developing countries. The trend is likely to continue in the near future and could reach 4 million by 2020. Despite high population growth, the arable land for agricultural production has remained relatively stagnant (Bourke 1997, 2001) with concomitant intensification of land use and reduced fallow periods. Most agriculture systems in Papua New Guinea are variations of shifting cultivation systems, usually between 15 and 25 years long, compared to one to two years of cultivation. However, population pressure has resulted in reduction in fallow periods from several decades to less than one decade (Sam, 1996). In the long term, one can anticipate further shortening of fallow periods and lengthening of cropping cycles. There are already indications that soil fertility run-down is impacting on the productivity of the main staple in the area, sweet potatoes, which accounts for 55 to 90% of land under arable agriculture. However, at this stage it is still unclear wether the resource base ‘soil’ is indeed being depleted at a greater rate than it can be restored given the potentially high productivity of the soils in the region.

Kirchhof, G, Ramakrishna, A, & Bailey J.S. (2008). An evaluation of Colwell-P as a measure of plant available phosphorus in soils of volcanic and non-volcanic origin in the highlands of Papua New Guinea. Soil Use and Management. 24, 331-336.

Various soil test methods including Olsen, Colwell, Bray and Truog have been used to assess the levels of plant-available P (PAP) in soils situated in the highlands of Papua New Guinea (PNG). Up until now, though, there has been no guarantee that these tests provide valid assessments of PAP in these somewhat atypical organic matter-rich tropical soils. Furthermore, the critical soil-P concentrations associated with the tests have been based on studies conducted elsewhere in sub-tropical and temperate latitudes and as such may or may not be valid for soils or cropping situations in PNG. Soil (Colwell)- P and leaf-P data collected during a recent survey of sweet potato gardens in the highlands of PNG were therefore used to determine if useful relationships existed between these variables for different groups of soils, and if they do, to use these relationships to evaluate critical soil Colwell-P concentrations corresponding to a known critical concentration of P in sweet potato index leaf tissue. Separate, highly significant linear relationships were obtained between leaf-P and Colwell-P for soils of volcanic and non-volcanic origins. Based on these relationships, the critical Colwell-P concentration for volcanic soils was found to be four times greater than that for non-volcanic soils, presumably because much of the P extracted from the former soils with alkaline sodium bicarbonate had been chemically ‘fixed’ via sorption and precipitation reactions with sesquioxides and rendered unavailable to plants at ambient soil pH. These critical Colwell-P concentrations if adopted as benchmark values for the soil groups in question should ensure that the results of future soil fertility surveys involving Colwell-P assessments are correctly interpreted.

Ramakrishna, A. & Kirchhof, G. (2008). An evaluation of nutritional constraints on sweet potato (Ipomoea batatas) production in the central highlands of Papua New Guinea. Plant and Soil. 316, 97-105.

Sweet potato (Ipomoea batatas) is the staple food crop in the highlands of Papua New Guinea (PNG). Declining crop productivity, however, appears to be threatening the sustainability of sweet potato-based farming systems within the region, a probable cause being the exhaustion of soil nutrient reserves in continuously cultivated sweet potato gardens. To assess the extent of the problem, a survey of sweet potato gardens was conducted across four of the highlands provinces and information on soil and crop variables was obtained for old gardens (cultivated over many seasons) and new gardens (newly brought into cultivation) on soils of volcanic and non-volcanic origin. Crop leaf nutrient data collected in the survey were interpreted using the Diagnosis and Recommendation Integrated System (DRIS), to try to identify the main nutritional constraints on tuber production in different garden types on soils of volcanic or non-nonvolcanic origin. The results suggested that K deficiency was the primary cause of poor crop production in almost a third of sweet potato gardens, but was more of a problem in old gardens than in new. Phosphorus deficiency was also a problem on volcanic soils, and S deficiency on non-volcanic soils. These latter deficiencies, however, were at least as prevalent in new gardens as in old. Important factors contributing to K and S depletion from garden systems were the removal of K and S-rich vines from cultivation areas, the shortening of fallow periods and the burning of weed and crop residues, the latter releasing S (SO2) to the atmosphere. Correction of K and S deficiencies may require the recycling of old vines back to sweet potato cultivation areas and the adoption of a zero-burn policy for fallow management. Correction of P deficiency may necessitate the use of P-accumulating fallow species, e.g. wild Mexican sunflower (Tithonia diversifolia), to extract the P fixed by sesquioxide and allophanic minerals.

Kirchhof, Odunze, Salako, SOIL MANAGEMENT PRACTISES IN THE NORTHERN GUINEA SAVANNA OF NIGERIA, IN: Soil fertility in sweet potato-based cropping systems in the highlands of Papua New Guinea, 2009, ACIAR Technical Reports 71, Editor G. Kirchhof, p43-48. (http://www.aciar.gov.au/publication/TR71)

A survey of soil management practices was conducted in the northern Guinea savanna of Nigeria. Fifteen villages were randomly selected from a geographical grid covering an area of 100 × 200 km located in the benchmark area of the Ecoregional Program for the Humid and Sub-humid Tropics of Sub-Saharan Africa. In each village the chief and several farmers were interviewed to assess their soil management methods and attitude towards the need to conserve soil. A total of 181 farmers were interviewed in late 1996. The most common crop rotation systems were food legumes with non-legume crops (40%), followed by monocropping (28%). Fifty-three per cent of the farmers who included food legumes in their rotations did so for soil fertility considerations, while 49% of the farmers who practised monocropping did so to maximise their output. These practices indicate that farmers were well aware of the importance of legumes for maintaining soil fertility. Only 2% of the farmers practised mulching with crop residue. The most common use of crop residue was for fodder, the remainder largely being used as building material or else burnt. As a consequence, soil surfaces were generally bare at the onset of the rainy season and hence prone to soil erosion. Ridging was the most important land preparation technique (88%), with farmers perceiving benefit in terms of improved crop emergence (56%) and water conservation (11%). Other benefits included weed control. Ridging was generally practised along contours, with most farmers citing soil conservation benefits, e.g. water conservation, and erosion control as the reasons for using contour ridging. Those farmers who purposely ridged up and down the slope did so for drainage purposes. All farmers used the same method to build ridges—the ridge from the previous year was cut in the middle and the two halves of neighbouring ridges were combined to form a new ridge in the furrow from the previous year. According to the farmers, this method controlled weeds and improved emergence. None of the farmers practised rebuilding old ridges, similar to permanent ridges. Such a practice might be acceptable to farmers in that it may be less labour intensive to rebuild partially collapsed ridges compared to reridging completely. Soil physical benefits from semi-permanent ridging would include increased soil structural stability, reduced soil compaction and increased root proliferation into the subsoil. Negative side effects might include reduced crop emergence and increased weed infestation. The most commonly used tools for soil preparation were hand hoes (80%), followed by draft animals (16%) and tractors (3%).

Salako, F. K., Tian, G., Kirchhof G. 2008. Soil chemical properties and crop yields on an eroded Alfisol managed with herbaceous legumes under yam-maize rotation. Nigerian Journal of Soil Science 18:1-9

This study was carried out in Ibadan, southwestern Nigeria between 1997 and 1999 to determine changes in soil chemical properties and yields on a previously eroded Alfisol. A factorial experiment in which legumes (Vigna unguiculata (cowpea), Mucuna pruriens and Pueraria phaseoloides) and residue management (burned and mulched residues) were factors was set up in two replicates of runoff plots. Yam was planted in 1997 and 1999 whereas maize + legume intercrops were planted in 1997. Soil properties measured were particle size distribution, pH, organic C, total N, Ca, Mg, Mn, exchangeable acidity and effective cation exchange capacity. There was increased acidity at the site. Soil chemical properties were significantly improved by burning of cowpea and Pueraria residues and mulching with Mucuna. Yam tuber yields of 14-18 t ha-1 in 1997 was

Total of more then 120 publications, including 45 in international peer reviewed Journals.

Education/Qualifications

2004

Graduate Certificate in Higher Education (Grad.Cert.), The University of Queensland, Brisbane

1994

Doctor of Philosophy (PhD), Applied soil physics, The University of Queensland, Brisbane

1984

Diplom Agrar Ingenieur (Dipl.Ing.agr) Majors in Soil Science and Plant Nutrition, Meteorology and Climatology, Biophysics and Radiation Biology, Agricultural Engineering, Fruit production. Hannover University, Germany
Certified Professional Soil Scientist (CPSS), CPAg (Certified Practicing Agriculturist (CPAg)

Work History and Experience

since 2007

Think Soils

Soil Scientist and Director

The University of Queensland

Honorary Research Consultant with the University of Queensland

2002 - 2006

The University of Queensland,School of Land and Food Sciences

Lecturer:

Research and development:

Administration and Management:

Consulting activities:

1998-2002

NSW Department of Agriculture, Tamworth (now NSW DPI)

Senior soil physicist:

Leader of the soil physics unit at the Tamworth Centre for Crop Improvement for research into soil structural degradation in Northern NSW. Team leader: NSW Agriculture dryland salinity program in northern NSW. Develop, conduct and collaborate on national and international research to assess the impact of land use practices on soil structural modification and suggest remedies to halt or reverse soil structural decline and dryland salinity

1996-1997

International Institute of Tropical Agriculture, IITA Ibandan, Nigeria

Head, soil physics unit. Research on soil management in sub-Sahelian Africa (soil and water conservation, soil erosion management, fallow and soil fertility management)

1991-1996

The University of Queensland, Department of Agriculture

Research Fellow:

Lead project scientist to develop soil management methods in rain fed lowland rice based cropping systems of Indonesia and the Philippines, funded by the Australian Centre for International Agricultural Research (ACIAR)

1988-1991

CASSIRO Ltd, Wauchope NSW

Soil Scientist:

CASSIRO Ltd was a Research and Development Company jointly owned by CSIRO and Gerard Cassegrain & Co (Wauchope, NSW). Lead scientist for the commercialisation of a subsoil amelioration technique to treat acid, sodic and degraded soils.

Memberships

Languages

German (native), English (fluent), French (rudimentary)