I. Effect of Nitrogen Rate on Plant Nitrogen Loss in Winter Wheat Varieties II. Glutamine Synthetase Activity in Winter Wheat Varieties III. Effect of Nitrogen Fertilization and Cation Removal on Soil pH

Soil Scienc

Potential Markets for Herbicide Resistant Maize Seed for Striga Control in Africa

Striga is an obligate parasitic weed attacking cereal crops in Subsaharan Africa. In Western Kenya, it is identified by farmers as their major pest problem in maize. A new technology, consisting of seed coating of herbicide tolerant maize varieties, has prove to be very effective in farmer fields. To bring this technology to the farmer, a sustainable delivery system needs to be developed, preferably through the private sector. To help of the seed companies develop a strategy, the potential market for this technology is hereby calculated, combines different data sources into a Geographic Information System (GIS). Superimposing secondary data, field surveys, agricultural statistics and farmer surveys makes it possible to clearly identify the Striga-prone areas in western Kenya. According to the analysis, the area has 212,000 ha in maize annually, with a population of 5.9 million people and a maize production of 480,000 kg, or 81 kg/person. Population density is high at 359 people/km2. A farmer survey reveals that 70% of farmers in this zone have Striga in their fields. Contingent valuation methods indicate that farmers' would be willing to buy on average 3.67 kg of the new seed each. This translates into a potential demand of 3,400 to 5,200 tons annually. Similar calculations, but based on much less precise data and expert opinion, not farmer surveys, estimate the potential market for herbicide tolerant maize against Striga at 64,600 tons annually, with an estimated value of $129 million.maize, Striga, Africa, weeds, pest control, Crop Production/Industries, Q12,

Participatory Evaluation of Integrated Pest and Soil Fertility Management Options Using Ordered Categorical Data Analysis

During participatory rural appraisals, farmers at the Lake Victoria basin of Kenya and Uganda identified Striga, stemborer and declining soil fertility as three major constraints to maize production To reduce food insecurity, several innovative integrated technologies to address these constraints have been developed, including push-pull (maize intercropped with Desmodium and surrounded by napier grass), maize-soybean and maize-crotalaria rotations, and Imazapyrresistant (IR) maize seed coated with the herbicide. To let farmers evaluate the new technologies, 12 demonstration trials, comparing the different technologies, were established in four villages in Siaya and Vihiga districts (Western Kenya) and two villages in Busia (Uganda). These evaluations, where farmers' appreciation and feedback on the technology are captured, are an important step in technology development. During field days at the end of short rainy seasons of 2003 and 2004, 504 farmers individually observed and rated each treatment under the different cropping systems, with and without IR maize, and with and without fertilizer, with a maize continuous monocrop as control. Farmers scored each of the 16 treatments on an ordered scale of five categories: very poor, poor, average, good, and very good. The treatments were scored for each of the criteria farmers has previously determined (including yield, resistance to Striga and stemborer, and improvement of soil fertility). Analysis of the evaluation, using ordinal regression, show significant differences in farmers' preference by year and site. There was, however, little effect of farm and farmer characteristics such as farm size and gender of the observer. Ordinal regression of farmers' scores are not as intuitive and also bit cumbersome to use, but they have a better theoretical foundation than other methods, in particular the use of means. This paper shows how the method can be used, and concludes that, with some effort, it is a convenient way to analyse farmers' ranking of a large number of options.farmers' preference, technologies, ordinal regression, Crop Production/Industries,

Effective Striga control and yield intensification on maize farms in western Kenya with N fertilizer and herbicide-resistant variety

Context: Maize production in western Kenya is limited by the spread of parasitic weed Striga hermonthica and depletion of soil nutrient stocks. Nitrogen (N) fertilizer and imidazolinone resistant (IR) maize are key elements in the agronomic toolbox to control infestations and enhance yieldsResearch question: The circumstances under which their use, individually or combined, is most effective on farmer fields have not been well documented. Inappropriate management decisions and low returns on investments arise from this knowledge gap, causing hunger and poverty in smallholder communities to persist.Methods: Experiments were carried out on 60 fields in three different agroecosystems of western Kenya using full-factorial treatments with non-herbicide treated maize (DH) and herbicide treated maize (IR), and N fertilizer omission and application. Trials were stratified on a field with low and high soil fertility within individual farms and repeated over two seasons.Results: Cultivating IR maize instead of DH maize decreased the emergence of Striga with 13 shoots m(-2) on average while applying N fertilizer on DH maize led to a reduction of 5 shoots m-2 on average. Decreases of Striga by use of IR maize and N fertilizer were between 6 and 23 shoots m(-2) larger at the site with high levels of infestation than at the sites with medium or low emergence. Input of N fertilizer increased grain harvests by 0.59 ton ha(-1) on average while use of IR maize enhanced the productivity with 0.33 ton ha(-1) on average. Use of N fertilizer had similar yield effects in all three sites, whereas use of IR maize at the site with high Striga emergence increased maize production by 0.26-0.39 ton ha(-1) more than at the sites with medium or low emergence.Conclusions: The greater Striga responses to IR maize and the greater yield responses to N fertilizer demonstrate their use could be optimized according to field conditions and management goals. Combining IR maize and N fertilizer has larger added yield benefits where their individual effects on grain productivity are smaller. Significance: Findings from this study indicate that farmers in western Kenya require guidance on how to align the use of herbicide resistant maize and inorganic N inputs with the level of Striga infestation and maize yield on their fields for effectively controlling the pernicious weed and enhancing food production

The role of nitrogen fixation in African smallholder agriculture

African smallholders face a conundrum! They spend their whole life surrounded by air which is 79% nitrogen gas and yet their crops are yellow and starved of nitrogen. The biological fixation of nitrogen by legumes offers a pathway for smallholders to access this infinite source of nitrogen. Yet current input of nitrogen fixation in African smallholder systems is very limited – often much less than 10 kg N ha−1 when calculated across the whole farm.Legumes are a key component of pathways to the Sustainable Intensification of agriculture: they provide food, fodder other products such as fuelwood and stakes and improve soil fertility (Vanlauwe et al., 2014). Further, legumes offer the opportunity to diversify monotonous diets, as protein and micronutrient dense food and to diversify cropping systems often built on monocultures of cereals or root and tuber crops. In Africa, rates of nitrogen fixation by grain legumes as high as 250 kg N ha−1 have been measured in experimental fields, demonstrating their huge potential. Lastly, the sale of legume grains contributes substantially to household income in major legume production areas.Against a backdrop of a rapidly growing population and decreasing farm size, a large pan-African collaborative project was initiated in 2009. The project entitled: Putting nitrogen fixation to work for smallholder farmers in Africa: N2Africa works across a wide range of agroecological conditions across 11 countries of sub-Saharan Africa. N2Africa is conceived as a “development-to-research” project in which grain legume technologies emerging from research are disseminated and tested at scale with many thousands of farmers (Giller et al., 2013). Through a structured and targeted approach N2Africa seeks to understand where, when, why and for whom approaches to the intensification and diversification of farming using different grain legume technologies work best. A key concept is the socio-ecological niche – recognizing the rich diversity of agroecologies, societies and cultures to enable the matching of technologies to farming systems, farms and fields (Ojiem et al., 2006).This Special Issue brings together a series of papers based on recent research on N2-fixation by grain legumes and its wider benefits across sub-Saharan Africa. The final chapter (Vanlauwe et al., 2014) reflects on the contributions and highlights issues requiring the attention of research in future

Potential Markets for Herbicide Resistant Maize Seed for Striga Control in Africa

Striga is an obligate parasitic weed attacking cereal crops in Subsaharan Africa. In Western Kenya, it is identified by farmers as their major pest problem in maize. A new technology, consisting of seed coating of herbicide tolerant maize varieties, has prove to be very effective in farmer fields. To bring this technology to the farmer, a sustainable delivery system needs to be developed, preferably through the private sector. To help of the seed companies develop a strategy, the potential market for this technology is hereby calculated, combines different data sources into a Geographic Information System (GIS). Superimposing secondary data, field surveys, agricultural statistics and farmer surveys makes it possible to clearly identify the Striga-prone areas in western Kenya. According to the analysis, the area has 212,000 ha in maize annually, with a population of 5.9 million people and a maize production of 480,000 kg, or 81 kg/person. Population density is high at 359 people/km2. A farmer survey reveals that 70% of farmers in this zone have Striga in their fields. Contingent valuation methods indicate that farmers' would be willing to buy on average 3.67 kg of the new seed each. This translates into a potential demand of 3,400 to 5,200 tons annually. Similar calculations, but based on much less precise data and expert opinion, not farmer surveys, estimate the potential market for herbicide tolerant maize against Striga at 64,600 tons annually, with an estimated value of $129 million

The devil is in the detail! : Sustainability assessment of African smallholder farming

Indicators for sustainability are a hot and debated topic. Sustainable intensification of agriculture is also widely debated due to the divergent views on the future of agriculture and the wide variety of indicators used. Legumes are seen as a key option for sustainable intensification of smallholder farming systems in sub-Saharan Africa (SSA). We developed a framework for assessing the sustainability of contrasting farming systems to illustrate the complex balancing act involved, using a case study of the N2Africa project. N2Africa offers legume options to farmers in SSA (www.N2Africa.org). We worked at farm household level and used a hierarchical framework of principles and criteria to select the indicators for sustainability. One of the main outcomes is a list of questions and hurdles we ran into when developing the framework. This can be used by others as guidance both when choosing indicators and to critically evaluate existing sustainability assessments. We illustrate that many of the decisions made in developing an indicator framework are subjective and that they include important but easily overlooked details. We conclude that, only by being explicit about the steps taken and the assumptions and decisions made, one can develop a sustainability framework that results in meaningful outcomes. </p