A diffusion model for the adoption of agricultural innovations in structured adopting populations

We introduce a new model for examining the dynamics of uptake of technological innovations in agricultural systems, using the adoption of zero-till wheat in the rice-wheat system in Haryana state, India, as a case study. A new equation is derived which describes the dynamics of adoption over time and takes into account the effect of aggregation (e.g. on a spatial and/or cultural basis) in the adopting population on the rate of adoption. The model extends previous phenomenological models by removing the assumption of homogeneity in the non-adopting fraction of the population. We show how factors affecting the per capita rate of adoption can be captured using cognitive mapping and simulate the dynamics of the adoption process.Bass curve, adoption, innovation, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

On the political economy of plant disease epidemics : Capita selecta in historical epidemiology door J.C. Zadoks

Dit boek brengt een aantal casussen bijeen waarin de invloed van epidemieën van plantenziekten op de mens en de maatschappij nader bestudeerd wordt. ‘Political economy’ refereert hier naar een term uit de achttiende eeuw die tegenwoordig vooral gebruikt wordt voor de studie van economische en politieke veranderingen met behulp van diverse, interdisciplinaire en vaak onconventionele benaderinge

The role of cattle manure in enhancing on-farm productivity, macro- and micro-nutrient uptake, and profitability of maize in the Guinea savanna

An on-farm trial was conducted in the northern Guinea savanna of Nigeria, over a period of five years, with the objectives of quantifying the effects on maize of applying cattle manure in combination with synthetic fertilizer with regard to soil characteristics, yield, plant nutrition and profitability. Maize grain yield was significantly increased by the annual application of cattle manure, compared to maize receiving an equal amount of N through synthetic fertilizer, but only from the third year of the experiment. The application of manure resulted in higher soil Kjel N, Bray-I P and exchangeable K values, and an increased N utilization efficiency by maize, suggesting that yield-limiting factors other than N deficiencies were of lesser importance than in the treatment receiving sole inorganic fertilizer. Nutrients other than N applied via the manure, particularly P, K and/or B, may have contributed to the higher grain yields in treatments receiving manure. A partial budgeting analysis revealed that, over a 5-year period, investments in the application of manure, in combination with synthetic fertilizer, resulted in higher margins than the application of fertilizer alone. However, analyses of marginal rates of return of changes from low urea N to high urea N or additional manure applications suggested that it was more profitable to invest in additional urea than in organic manure in the first two years of the experiment. The results suggested that manure applications, even when applied at relatively high rates, did not serve as a quick fix to on-farm soil fertility problems, but over a longer period, manure applied in combination with synthetic fertilizers did provide a significant and profitable contribution to enhanced cereal production

A comparison between legume technologies and fallow, and their effects on maize and soil traits, in two distinct environments of the West African savannah

Legume¿maize rotation and maize nitrogen (N)-response trials were carried out simultaneously from 1998 to 2004 in two distinct agro-ecological environments of West Africa: the humid derived savannah (Ibadan) and the drier northern Guinea savannah (Zaria). In the N-response trial, maize was grown annually receiving urea N at 0, 30, 60, 90 and 120 kg N ha¿1. In Ibadan, maize production increased with N fertilization, but mean annual grain yield declined over the course of the trial. In Zaria, no response to N treatments was observed initially, and an increase in the phosphorus (P) and sulphur (S) fertilizer application rate was required to increase yield across treatments and obtain a response to N applications, stressing the importance of non-N fertilizers in the savannah. In the rotation trial, a 2-year natural fallow¿maize rotation was compared with maize rotated with different legume types: green manure, forage, dual-purpose, and grain legumes. The cultivation of some legume types resulted in a greater annual maize production relative to the fallow¿maize combination and corresponding treatments in the N-response trial, while there was no gain in maize yield with other legume types. Large differences in the residual effects from legumes and fallow were also observed between sites, indicting a need for site-specific land management recommendations. In Ibadan, cultivation of maize after the forage legume (Stylosanthes guianensis) achieved the highest yield. The natural fallow¿maize rotation had improved soil characteristics (Bray-I P, exchangeable potassium, calcium and magnesium) at the end of the trial relative to legume¿maize rotations, and natural fallow resulted in higher maize yields than the green manure legume (Pueraria phaseoloides). In Zaria, maize following dual-purpose soybean achieved the highest mean yield. At both sites, variation in aboveground N and P dynamics of the legume and fallow vegetation could only partly explain the different residual effects on maiz

Deskstudie biologische bestrijding van invasieve exotische oever- en wateronkruiden in Nederland

In dit rapport wordt een overzicht gegeven van biologische onkruidbestrijding in het algemeen, en ontwikkelingen op het gebied van biologische bestrijding van elf belangrijke exotische oever- en wateronkruiden in Nederland in het bijzonder. Twee relevante casussen worden nader belicht: de graskarper en de waterhyacin

Does crop-livestock integration lead to improved crop production in the savanna of West Africa?

Integrated crop-livestock farming in the Guinea savanna of West Africa is often assumed to lead to synergies between crop and livestock production, thereby improving the overall productivity and resilience of agricultural production. Whether these synergies actually occur remains poorly studied. On-farm trials were conducted in northern Nigeria over a period of four years to assess the agronomic and economic performance of maize-legume systems with and without the integration of livestock (goats). Groundnut-maize rotations with livestock achieved the highest carry-over of nutrients as manure from one season to the next, covering approximately one-third of the expected N, P and K uptake by maize and reducing the demand for synthetic fertilizers. However, the advantage of lower fertilizer costs in rotations with livestock was offset by higher labour costs for manure application and slightly lower values of maize grain. Overall, no clear agronomic or economic benefits for crop production were observed from the combined application of manure and synthetic fertilizer over the application of synthetic fertilizer only, probably because the amounts of manure applied were relatively small. Legume-maize rotations achieved higher cereal yields, a better response to labour and fertilizer inputs, and a higher profitability than maize-based systems with no or only a small legume component, irrespective of the presence of livestock. Livestock at or near the farm could nevertheless make legume cultivation economically more attractive by increasing the value of legume haulms. The results suggested that factors other than crop benefits, e.g. livestock providing tangible and non-tangible benefits and opportunities for animal traction, could be important drivers for the ongoing integration of crop and livestock production in the savann

Inventory of observed unexpected environmental effects of genetically modified crops

In general, it can be concluded that very few clearly unexpected effects were observed during the large scale post-release growing of herbicide-tolerant crops and Bt crops. Of course, one has to keep in mind Applied Plant Research (Praktijkonderzoek Plant & Omgeving ) 14 that there will always be an element of subjectivity in assessing effects as “unexpected”. Furthermore, it is also possible that certain effects are becoming visible only after a longer period than 10 – 15 years, but no indications for such effects were found in the literature. Besides the reports about the Farm Scale Evaluations no other reports were found with information about effects of GM crops on biodiversity in ecosysystems surrounding the production fields. Unexpected effects caused directly by the genetic modification were not found. Only in herbicide-tolerant crops, we concluded to some indirect unexpected effects: the reduced uptake of micro-nutrients and some positive and negative effects on susceptibility to diseases. These effects were specific to herbicide use with glyphosate-tolerant crops. Based on this, it was not possible to draw general conclusions for developing protocols for post-release monitoring of environmental effect