Ken Giller

Ken Giller
Wageningen University & Research | WUR · Department of Plant Production Systems

BSc, PhD

About

767
Publications
346,219
Reads
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43,259
Citations
Introduction
We have an ebook version available - see https://www.globalacademicpress.com/ebooks/N2/ We are pleased to share “The Story of N2Africa” - an online magazine that provides a flavour of the richness of learning over the past ten years of the project N2Africa: Putting nitrogen fixation to work for smallholder farmers in Africa https://magazines.wur.nl/n2africa/welcome/ Please share widely using #N2Africa
Additional affiliations
September 2001 - present
Wageningen University & Research
Position
  • Professor of Plant Production Systems
September 2001 - March 2015
Wageningen University & Research
Position
  • Professor of Plant Production Systems
September 2001 - October 2001
Wageningen University & Research
Position
  • Professor of Plant Production Systems

Publications

Publications (767)
Article
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Global support for Conservation Agriculture (CA) as a pathway to Sustainable Intensification is strong. CA revolves around three principles: no-till (or minimal soil disturbance), soil cover, and crop rotation. The benefits arising from the ease of crop management, energy/cost/time savings, and soil and water conservation led to widespread adoption...
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We calculated a simple indicator of food availability using data from 93 sites in 17 countries across contrasted agroecologies in sub-Saharan Africa (>13,000 farm households) and analyzed the drivers of variations in food availability. Crop production was the major source of energy, contributing 60% of food availability. The off-farm income contrib...
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Agriculture is in crisis. Soil health is collapsing. Biodiversity faces the sixth mass extinction. Crop yields are plateauing. Against this crisis narrative swells a clarion call for Regenerative Agriculture. But what is Regenerative Agriculture, and why is it gaining such prominence? Which problems does it solve, and how? Here we address these que...
Article
Maize-grain legume intercrops form an important component of the cropping systems of smallholder farmers in many parts of sub-Saharan Africa. However, the effects of cropping system and fertilizer use on nitrogen fixation and nitrogen uptake of component crops in maize-legume intercrops are not well understood. Our study addressed the questions: (i...
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Production of cereals (maize, sorghum, millet) in southern Mali is challenged by several hazards that affect yield and yield variability. The research aims to inform decision making towards effective risk management by quantifying cereal yield losses at field level due to production hazards under different management strategies. Five hazards releva...
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Intercropping of maize with grain-legume crops predominates on smallholder farms in East Africa. However, the growth and development of crops and their interaction with fertilizer in intercropping systems are not well understood. We sought to answer the questions: (i) what are the effects of fertilizer on the growth and development of maize-pigeonp...
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Current process-based approaches to regulation are no longer fit for purpose.
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Inland valleys (IVs) in West African countries have increasingly been used for crop production, including rice cultivation. Though it is widely assumed that IVs have a high potential to contribute to food security of West African countries, a comprehensive assessment of farming systems addressing agricultural, institutional, food security, poverty,...
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The poultry industry in Tanzania has grown steadily over the past decade. We surveyed 121 chicken farming households along an intensification gradient from backyard to semi-intensive and intensive production systems based on rearing system and assumed purpose and poultry breed in the Iringa region. About 30% of households had more than one breed an...
Article
In November 2014 I suffered a major stroke and was unable to work. I recently began to ‘wake up’ and have been able to re-engage with literature and discussions on agricultural development and climate change. I am surprised how familiar I am with much of the debate, but disappointed that major issues receive little attention – such as the impacts o...
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With many of the world’s poor engaged in agriculture, agricultural development programmes often aim to improve livelihoods through improved farming practices. Research on the impacts of agricultural technology interventions is dominated by comparisons of adopters and non-adopters. By contrast, in this literature study, we critically review how tech...
Article
p>Wetlands in drylands are important resources for agriculture and wildlife, but competition may result in human–wildlife conflict. We sought to understand conditions under which people and wildlife sharing wetlands in drylands may coexist. We applied track counts in riverine wetlands in the dry and wet season (n = 36 days) using belt transects, fo...
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A solid understanding of the dynamics of plant nutrient requirements and uptake from the soil is needed to provide robust fertilizer recommendations, timing of applications and nutrient use efficiency. Our objective was to develop and test the ability of the crop model LINTUL-Cassava-NPK to simulate biomass growth and yield of cassava under nutrien...
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Background The demand for estimates of biological nitrogen (N) fixation inputs in agricultural systems is driven by the need to effectively manage the global N cycle. Scope We present a methodology for quantifying N2 fixation by the grain legume-rhizobia symbioses that can be used for any year or sequence of years for which area and production sta...
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The South African policy sphere hails the commercialisation of small-scale farming as the answer to a myriad of socio-economic, ecological and political challenges of rural livelihoods. Yet the low agricultural productivity of this sector challenges the realisation of this pathway. Through comparison with large-scale farmers, this review sought to...
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Background Cowpea is a grain legume of major importance in sub-Saharan Africa where it is cultivated by smallholder farmers on poor soils and production is often constrained by the parasitic weed Striga gesnerioides . Method Experiments were conducted to assess the potential of rhizobium inoculation to mitigate Striga infection and increase cowpea...
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The production and trade of agricultural commodities is a major driver of the loss of tropical biodiversity. In the Mid Zambezi Valley, Zimbabwe, which is home to many emblematic African mammals, cotton production has historically been a major driver of land cover change. The collapse of cotton production in Zimbabwe over the last decade provides a...
Article
Attention to soil biodiversity and its importance for sustainable food production has markedly increased in recent years. In particular, the loss of soil biodiversity as a consequence of intensive agriculture, land degradation and climate change has raised concerns due to the expected negative impacts on ecosystem services, food security and human...
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Crop residues have the potential to alleviate annual feed shortages and nutrient deficiencies experienced in the dry season in the savanna zones of West Africa. Farmers in West Africa especially value the residues of grain legumes, also known as grain legume fodders (GLFs), as animal feed. In this study, therefore, we assessed the nutritional quali...
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East African highland banana ( Musa acuminata genome group AAA-EA; hereafter referred to as banana) is critical for Uganda’s food supply, hence our aim to map current distribution and to understand changes in banana production areas over the past five decades. We collected banana presence/absence data through an online survey based on high-resoluti...
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Agriculture faces many challenges. In both public discourse and the scientific literature debates about the future are increasing framed in terms of ‘alternative’ versus ‘conventional’ agriculture. In this paper we critically examine this framing, and seek to understand how the term conventional has been and is being used. We argue that the categor...
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Smallholder farming in sub-Saharan Africa keeps many rural households trapped in a cycle of poor productivity and low incomes. Two options to reach a decent income include intensification of production and expansion of farm areas per household. In this study, we explore what is a “viable farm size,” i.e., the farm area that is required to attain a...
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Background We collated estimates of the percentage of legume N derived from atmospheric N2 (%Ndfa) for 14 major grain legumes and then analysed and aggregated the data to derive average values for different crops and regions/countries. The effects of cultivation year and whether data collected from experimental plots were relevant to crops growing...
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Leguminous plants are known to require phosphorus fertilizers and inoculation with nitrogen fixing rhizobia for optimum yield but other nutrients may also be lacking. In this study, the most limiting nutrients for legume growth were determined in soils where the crops had not responded to P and rhizobial inoculation in field trials, using the doubl...
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In South-West Uganda, manure is highly valued for sustaining yields of East African Highland Banana, but it is in short supply. As a result, banana growers import manure from rangelands up to 50 km away. We aimed to explore the potential of this regional banana-livestock integration to meet crop nutrient requirements for sustainable intensification...
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Motivation Most transaction cost economic frameworks, commonly used to examine and explain the co-ordination of agricultural transactions, use a linear approach for a single product transaction. This ignores the concurrence of multiple transactions by smallholder farmers in developing countries. Purpose This study aims to understand co-ordination...
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Most food in sub-Saharan Africa is produced on small farms. Using large datasets from household surveys conducted across many countries, we find that the majority of farms are less than 1 ha, much smaller than previous estimates. Farms are larger in farming systems in drier climates. Through a detailed analysis of food self-sufficiency, food and nu...
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It is often claimed that cocoa producers are poor, but the extent of their poverty is rarely defined. We analyzed six data sets derived from household questionnaires of 385–88,896 cocoa producers in Côte d'Ivoire and Ghana. Across all data sets, many households (30–58%) earn a gross income below the World Bank extreme poverty line and the majority...
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Poor soil fertility is a major problem constraining crop productivity in smallholder farms of sub-Saharan Africa due to inadequate nutrient replenishment. Differential management of nutrients creates areas of accumulation and depletion of nutrients within farms with the latter increasing in spatial coverage. Nutrient additions are required to incre...
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In Tanzania, diets are dominated by starchy staple crops such as maize, levels of malnutrition are high and largely attributed to lack of dietary diversity. We employed fuzzy cognitive mapping to understand the current soybean, maize and chicken value chains, to highlight stakeholder relationships and to identify entry points for value chain integr...
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Achieving SDG2 (zero hunger) in a situation of rapid global population growth requires a continued focus on food production. Farming not merely needs to sustainably produce nutritious diets, but should also provide livelihoods for farmers, while retaining natural ecosystems and services. Rather than focusing on production principles, this article e...
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Sustainable intensification has been proposed as a pathway to achieve food security and reduce environmental impacts of agriculture by focusing on narrowing yield gaps on existing agricultural land while improving resource use efficiencies. There is a general consensus that regions with large yield gaps can benefit most from sustainable intensifica...
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The 4th Global Food Security conference highlighted four major developments: the shift from food security to food systems; a focus on diets and consumption patterns; the importance of unknown futures and inherent uncertainties and risks; and the central role of multi-level connections between local-and global-oriented research. These shifts highlig...
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How to stimulate technological change to enhance agricultural productivity and reduce poverty remains an area of vigorous debate. In the face of heterogeneity among farm households and rural areas, one proposition is to offer potential users a 'basket of options'-a range of agricultural technologies from which potential users may select the ones th...
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Aim Recycling of cocoa pod husks has potential to contribute to mineral nutrition of cocoa. Yet little is known of the nutrient content and nutrient release patterns from the husks. The potassium (K) rich husks are usually left in heaps in cocoa plantations in Africa. We aimed to understand and quantify release patterns of K and other nutrients fro...
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Little is known about productivity of smallholder maize–pigeonpea intercropping systems in sub-Saharan Africa. We conducted a survey of 277 farm households in Northern Tanzania to assess socio-economic factors, field management characteristics, and their association with productivity of maize–pigeonpea intercrops. On each farm, crop assessments wer...
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A diet containing insufficient micronutrients can harm human health. Maps that pinpoint areas of Africa associated with micronutrient-poor grains now offer a way to target interventions that tackle such deficiencies. Maps pinpoint African regions associated with micronutrient-poor grain.
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Nitrogen (N) is an essential but generally limiting nutrient for biological systems. Development of the Haber-Bosch industrial process for ammonia synthesis helped to relieve N limitation of agricultural production, fueling the Green Revolution and reducing hunger. However, the massive use of industrial N fertilizer has doubled the N moving through...
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Crop production is at the core of a ‘perfect storm’ encompassing the grand challenges of achieving food and nutrition security for all, in the face of climate change, while avoiding further conversion of natural habitats for agriculture and loss of biodiversity. Here, we explore current trends in crop modelling related to these grand challenges by...
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Chickpea (Cicer arietinum L.) used to be considered a restrictive host that nodulated and fixed nitrogen only with Mesorhizobium ciceri and M. mediterraneum. Recent analysis revealed that chickpea can also establish effective symbioses with strains of several other Mesorhizobium species such as M. loti, M. haukuii, M. amorphae, M. muleiense, etc. T...
Preprint
Full-text available
Cowpea is a grain legume of major importance in sub-Saharan Africa where it is cultivated by smallholder farmers on poor soils and production is often constrained by the parasitic weed Striga gesnerioides . Experiments were conducted to assess the potential of rhizobium inoculation in mitigating Striga infestation and increasing cowpea productivity...
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Rhizobia are soil borne bacteria that form symbiotic relations with legumes and fix atmospheric nitrogen. The nitrogen fixation potential depends on several factors such as the type of host and symbionts and on environmental factors that affect the distribution of rhizobia. We isolated bacteria nodulating common bean in Southern Ethiopia to evaluat...
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The use of options for sustainable intensification of smallholder farming in sub-Saharan Africa is often limited by knowledge and resource constraints. To address both constraints, we developed and tested an integrated co-learning approach to improve farm level productivity. The approach was tested by differentiating a group of co-learning farmers...
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Accurate assessments of the yield potential of cassava are needed to analyse yield gaps, define yield targets and set benchmarks for actual yields in Nigeria. This study evaluated the crop model LINTUL-Cassava under assumed potential growth and water-limited conditions in Nigeria. On-farm experiments were conducted at six locations across the three...
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East African highland bananas and climbing beans are important crops for food and income in the highlands of Uganda. Intercropping of banana with legume crops is a common practice, yet climbing bean intercropping with perennials has rarely been studied in Uganda. To understand how best to improve the production system, we assessed the effects of pr...
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Conservation Agriculture (CA) has been widely promoted as a pathway to sustainably intensify agriculture in sub-Saharan Africa (SSA). Yet despite decades of promotion, CA uptake in SSA remains sparse with only few analyses of its impacts on farming and rural livelihoods. This study, which focuses on areas in Central Malawi considered to have a rela...
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Fertilizers are required to improve productivity of cassava and meet the increasing demand for cassava as food, feed, or raw material for processing industries. Our objective was to develop nutrition indices for N, P, and K to provide quantitative insight in the dynamics of nutrient demand and uptake of cassava. On-farm experiments were conducted a...
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The world is challenged to meet the food demand of a growing population, especially in developing countries. Given the ambitious plans to scale up agroforestry in Africa, an improved understanding of the effect of agroforestry practices on the already challenged food security of rural households is crucial. The present study was undertaken to asses...
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Fertilizer recommendations are key for farmers: the investment is relatively large for smallholders and risky with unknown yield responses and variable fertilizer prices. Are agronomists able to provide useful site-specific fertilizer recommendations that reduce these uncertainties? We evaluated the influence of errors introduced due to soil sampli...
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Legume genotype (G L) x rhizobium genotype (G R) interaction in chickpea was studied using a genetically diverse set of accessions and rhizobium strains in modified Leonard Jars. A subset of effective G L x G R combinations was subsequently evaluated in a pot experiment to identify combinations of chickpea genotypes and rhizobium strains with stabl...
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In Africa, cocoa yields are low, partly due to soil fertility constraints and poor management. While peoples' knowledge, aspirations, and abilities are key factors explaining their behaviour, little is known about the rationales that underpin soil fertility management practices (SFMPs) of cocoa farmers. To address this gap, we conducted an explorat...