The use of mixed species cropping to manage pests and diseases – theory and practice

This paper was presented at the UK organic research 2002 on behalf of colloquium of Organic Researchers (COR). Mixed species cropping is often perceived as a viable tool to increase on-farm biodiversity in organic agriculture and is a potentially important component of any sustainable cropping system. Apart from increasing total farm productivity, mixed species cropping can bring many important benefits such as improvement of soil fertility management and suppression of pests and/or diseases. In this sense it can be seen as performing different eco-services in the farm system. This paper discusses mixed cropping in this context while focusing on its potential and actual use as a tool to manage pests and diseases in organic farming systems

Optimizing a green manure-based row cropping system for organic cereal production

A row cropping system with an increase of row distance to 24 cm increased the growth of undersown cover crops and allowed 1-2 passes of interow hoeing for weed control before sowing cover crops. The three-week delay sowing time was suitable for the growth of legume species. The new system significantly improved both grain yield and grain N content of the succeeding crop compared to the traditional cropping system

Determinants of Crop Choices by Bangladeshi Farmers: A Bivariate Probit Analysis

Using a bivariate probit model, the study jointly determines the factors underlying the probability of Bangladeshi farmers adopting a diversified cropping system and/or modern rice technology. Results reveal that the availability of irrigation is the single most important determinant of the decision to adopt modern rice technology, and adoption is higher among the tenant farmers. The exact opposite is true for the likelihood of adopting a diversified cropping system, which is significantly higher in areas with no irrigation as well as among the owner- operators. Furthermore, the diversified cropping system has a significantly higher rate of adoption in regions with developed infrastructure. Farmers' education, farming experience, farm asset ownership, and non-agricultural income all positively influence crop diversification. Also, small farmers are more likely to adopt a diversified cropping system. Significant regional variation exists in the level of crop diversification as well. The decision to adopt a diversified cropping system and/or modern rice technology is significantly correlated, implying that a univariate analysis of such decision is biased. Crop diversification can be promoted by investing in farmers' education as well as rural infrastructure development. Also, land reform policies focusing on delegating land ownership to landless and marginal farmers, and tenurial reforms are noteworthy.

Comparison of Risk Between Cropping Systems in Eastern Norway

The aim of this study was to compare production and policy risk of organic, integrated and conventional cropping systems in Norway. Experimental cropping system data (1991-1999) from eastern Norway were combined with budgeted data. Empirical distributions of total farm income for different cropping systems were estimated with a simulation model that uses a multivariate kernel density function to smooth the limited experimental data. Stochastic efficiency with respect to a function (SERF) was used to rank the cropping systems for farmers with various risk aversion levels. The results show that the organic system had the greatest net farm income variability, but the existing payment system and organic price premiums makes it the most economically viable alternative.organic, integrated and conventional crop farming, stochastic simulation, multivariate kernel estimator, risk aversion, stochastic efficiency with respect to a function, Crop Production/Industries, Risk and Uncertainty, Q12, C44,

Impact of cropping system on mycorrhiza

The impact of cropping system on field communities of mycorrhizal fungi was studied utilising a long-term experiment on a loamy soil. Two contrasting crop rotations each with two fertilisation regimes were compared. The conventional crop rotation (barley-barley-rye-oat-potato-oat) was fertilised at either full or half the normal recommended rate. In the low-input crop rotation, one year with barley was replaced by clover, and oat was cultivated in mixture with pea. For this rotation biotite and raw phosphate was used to compensate for the K and P of the harvested yield; animal manure was used at the beginning only. Clover and straw were returned to the soil either directly or after composting. Mycorrhizal infectivity and effectiveness were studied in bioassays in the growth chamber, and the spore densities of mycorrhizal fungi as well as their species composition in the field were determined. Only the low-input system with application of compost conclusively favoured mycorrhiza, in comparison to some or all of the other systems depending on time and function. The low-input system with no compost was more favourable than the conventional systems in terms of growth effect in 1996, but in 1997, clover incorporation markedly inhibited mycorrhiza in comparison to the other systems. Inhibition of mycorrhizal functions may indicate general mismanagement and imbalance in the soil ecosystem. This stresses the need for further studies on the importance of composting easily decomposable organic matter prior to soil incorporation for management of soil quality

RISK ANALYSIS OF CROPPING SYSTEMS USING EXPERIMENTAL CROPPING SYSTEM-FERTILIZER DATA

Using 11 years of experimental crop yields by cropping systems and fertilizer level, a MOTAD frontier was developed. This analysis allowed yield, cost, and stability interactions arising from crop sequences to be implicitly included. Target-MOTAD, Safety-First, and undominated stochastic efficient systems were also compared.Research Methods/ Statistical Methods, Risk and Uncertainty,

Can a change in cropping patterns produce water savings and social gains: A case study from the Fergana Valley, Central Asia

Abstract The study examines possible water savings by replacing alfalfa with winter wheat in the Fergana Valley, located upstream of the Syrdarya River in Central Asia. Agricultural reforms since the 1990s have promoted this change in cropping patterns in the Central Asian states to enhance food security and social benefits. The water use of alfalfa, winter wheat/fallow, and winter wheat/green gram (double cropping) systems is compared for high-deficit, low-deficit, and full irrigation scenarios using hydrological modeling with the HYDRUS-1D software package. Modeling results indicate that replacing alfalfa with winter wheat in the Fergana Valley released significant water resources, mainly by reducing productive crop transpiration when abandoning alfalfa in favor of alternative cropping systems. However, the winter wheat/fallow cropping system caused high evaporation losses from fallow land after harvesting of winter wheat. Double cropping (i.e., the cultivation of green gram as a short duration summer crop after winter wheat harvesting) reduced evaporation losses, enhanced crop output and hence food security, while generating water savings that make more water available for other productive uses. Beyond water savings, this paper also discusses the economic and social gains that double cropping produces for the public within a broader developmental context

Cropping system to limit blast disease in upland rice

Cropping system is an essential aspect to take into account to manage blast disease (caused by the fungus Magnaporthe oryzae). In addition to the selection of resistant cultivars, studies report opportunities to limit blast incidence by managing mineral amendment (N, Si, P, etc.), cultivar mixtures or other cropping system adaptations. In Madagascar, rice is the staple crop and food. Farmers traditionally grow irrigated or rainfed lowland rice wherever possible. In the mid-1980s, CIRAD and FOFIFA launched a research program for the highlands to extend upland rice growing areas in high elevation areas of the tropics. This program was consolidated with research on cropping practices that ensure the sustainability of upland rice based cropping systems in this poor and fragile environment. New varieties where obtained, adapted for rainfed cropping up to 1800 m altitude (Dzido et al., 2004). However, farmers had to face attacks of blast disease. Due to the small genetic basis of these varieties, the fungus quickly overcame resistant or tolerant lines selected by breeders. The ways of management of blast disease are very limited in a country like Madagascar where efficient solutions are often not suitable for farmers. Observations of blast epidemics in different regions made us consider the soil as a key factor for rice susceptibility. In a first experiment, we measured the potential of our very susceptible varieties to tolerate blast when cropped in different soil conditions. During two years, we transported volcanic soil from a very fertile area close to the experimentation site and where blast pressure is much lower. We observed a decrease of blast symptoms on rice cropped on that soil compared to the soil of the experimental site, both on leaves and panicles. That decrease was bound to a significant yield increase, demonstrating the importance of plant nutrition on blast incidence. Such results confirm those obtained in 1981 by Seguy et al. Our aim was then to develop cropping systems that could influence blast incidence through an improvement of soil functions. Direct seeded mulch based (DSMB) cropping systems were first used in Madagascar to limit erosion in upland areas. During 4 years, we compared blast epidemics between a traditional cropping system with ploughing each year and a DSMB cropping system, on a midsusceptible variety specific of the highlands conditions. Two fertilisation levels were also tested in these systems: zebu manure only and manure plus additional mineral fertiliser. A significant difference between the two systems was observed, both at leaf and panicle stage. Blast incidence was reduced in DSMB cropping system and, on the contrary to the traditional cropping system, the mineral fertilisation had no effect on blast in DSMB. N fertilisation is known for a long time as an essential factor in blast management. The fact that DSMB cropping system reduced the effect of N-fertilisation made us consider N as the determinant factor of the interaction between cropping system and blast incidence. The determinants of this interaction must then be explained to enable new and durable cropping systems to be developed to manage blast epidemics, in addition to cultivar improvement. This is the objectives of the starting project GARP (ANR-Systerra) which is conducted in Bolivia, Brazil, France, and Madagascar. Its aim is to quantify the interactions between cropping system, N-nutrition and blast resistance in upland rice. Hypotheses and preliminary results of the project will be presented. (Texte intégral

Native Grassland Conversion: the Roles of Risk Intervention and Switching Costs

We develop a real option model of the irreversible native grassland conversion decision. Upon plowing, native grassland can be followed by either a permanent cropping system or a system in which land is put under cropping (respectively, grazing) whenever crop prices are high (respectively, low). Switching costs are incurred upon alternating between cropping and grazing. The effects of risk intervention in the form of crop insurance subsidies are studied, as are the effects of cropping innovations that reduce switching costs. We calibrate the model by using cropping return data for South Central North Dakota from 1989 to 2012. Simulations show that a risk intervention that offsets 20% of a cropping return shortfall increases the sod-busting cost threshold, below which native sod will be busted, by 41% (or $43.7/acre). Omitting cropping return risk across time underestimates this sod-busting cost threshold by 23$24.35/acre), and hence underestimates the native sod conversion caused by crop production