Project Title: CARMSAT - Increasing the effectiveness of research on agricultural resource management in the semi-arid tropics by combining cropping systems simulation with farming systems research.

Project Supervisor: Dr Meri Whitaker

Funding Body: ACIAR

Admin Contact: Dr Bob McCown

Commencement Date: 01/01/96 Completion Date: 31/12/2000

The goal of CARMASAT is to develop a farming systems research capability in ICRISAT that combines simulation of crop production systems with agronomic experimentation and socioeconomic research and to use this capability to enhance ICRISAT’s research on improved management of crops and production resources in the SAT of Asia and Africa.

The productivity of dryland crop production systems throughout the SAT is in decline due largely to farmer practices that result in mining of soil fertility. ICRISAT’s research team sin six agro-ecological regions have each identified needs for collaboration in simulation modelling to aid research aimed at improving crop and soil management. One or more of the following issues cut across all six proposals:

• the need for better management in relation to soil water, N, and/or P constraints in production of various crops,
• need for better management in relation to soil degradation caused by erosion and depletion of organic matter, and
• the apparent reluctance of farmers to invest in soil fertility inputs and soil conservation to maintain or improve soil productivity.

For models to meet the needs identified in this research, they need to simulate: growth and yield of important crops; runoff and soil erosion; long-term trends in soil organic matter; soil dynamics and supply to plants of water, N, and P; effects of residues, manure and fertilisers; interactions of crops in mixtures, relays, and sequences; seedling stresses and mortality; density and tillering/branching effects on resource sharing; and conditional crop and soil management actions. The Agricultural Production Systems Simulator (APSIM) developed by APSRU for use in the Australian semi-arid tropics and subtropics does most of this at the outset and will be developed to do the rest early in this project. Essential roles of CARMASAT are to maintain APSIM (as a reliable software package for ICRISAT users), test and adapt APSIM modules for the conditions in ICRISAT projects, lead the development of new modules (eg., pigeonpea, millet, soil P, manure) within Modelling Working Groups and provide documentation and training for APSIM users in systems projects.

In CARMASAT, APSIM will be used primarily in two research modes. The first to assist cropping systems research in terms of soil water, N and P economies, soil organic matter trends, soil erosion, crop adaptation, and yield variability and trends. Support will be given to scientists adding value to their experiments through simulation to extrapolate to seasons and places outside the boundaries of the experiment.

These second research mode using models is the evaluation of farm management options in terms of yields, returns, rates of soil loss an degradation. This work is done with farmers, NARS professional and NGOs in farm case studies and, in addition to APSIM, involves complementary input of economists with whole farm models. The work proceeds in the following steps: select farms and households (near long-standing, proximate weather station), develop economic model of farm, negotiate and conduct experiments with farmers, and to establish credibility of APSIM by simulation experiments, using APSIM and the economic model, to engage farmers and advisers in What if? Analysis and discussions on important issues, and to document both the analyses and the discussions.

This collaboration will provide opportunities for new insights on matters of importance in Australia. The issue in Asia and Africa of declining productivity and the apparent reluctance of farmers to invest in its increase is also a serious issue in the subtropical region of eastern Australia which is the mandate region for APSRU. One of the opportunities offered by CARMASAT is that of a closer involvement of socioeconomists with agronomist/modellers than has been achievable in Australia. Progress in understanding of farmer investment behaviour in CARMASAT will provide important inputs to better understanding in Australia. The development of APSIM represents a major investment by Australian standards, and the fact that APSIM is already being used in all mainland Australian States indicates its potential in Australian R&D. CARMASAT will build on two successful ACIAR projects which have terminated (one on farming systems in the Kenyan semi-arid tropics and one on management of alfisols conducted at ICRISAT). The component of CARMASAT located in Kenya will be conducted with collaborators in KARI that were trained in Queensland as part of ACIAR projects 8326 and 8735.