Combining Manure with Mineral N Fertilizer Maintains Maize Yields: Evidence from Four Long-Term Experiments in Kenya
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Date
2023
Authors
Laub, Moritz
Corbeels, Marc
Ndungu, Samuel Mathu
Mucheru-Muna, Monicah Wanjiku
Mugendi, Daniel
Necpalova, Magdalena
De Broek, Marijn Van
Waswa, Wycliffe
Vanlauwe, Bernard
Six, Johan
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Context: Crop productivity in sub-Saharan Africa cannot be substantially improved without simultaneously
addressing short-term crop nutrient demand and long-term soil fertility. Integrated soil fertility management
tackles both by the combined application of mineral fertilizers and organic resource inputs but few studies
examined its‘ long-term effectiveness.
Objective: To address this knowledge gap, this study analysed maize yield trends in four long-term (31–37
cropping seasons) field experiments in Kenya with contrasting soil textures and under different climates.
Methods: All sites had two maize cropping seasons per year, received a base P and K fertilization and tested
combinations of organic resource addition (1.2 and 4 t C ha-1 yr-1 ranging from farmyard manure, to high-quality
Tithonia diversifolia and Calliandra calothyrsus material to low-quality saw dust), combined with (+N) and
without (-N) mineral N fertilizer (120 kg N ha-1 season-1). General maize yield trends across sites and site specific
trends were analyzed.
Results: Across sites, the no-input control experienced significant average maize yield reductions of 50 kg ha-1 yr-1
over the study period. In contrast, the treatment with farmyard manure +N maintained yields at both 1.2 and 4 t
C ha-1 yr-1. High initial yields following additions of Tithonia and Calliandra, reduced over time. Assessment by
site showed site specificity of maize yields and yield trends. For example, the two climatically favorable sites in
western Kenya experienced yield gains with high quality organic resources at 4 t C ha-1 yr-1, leading to yields of
up to 8 t ha-1 per season, while sites in central Kenya experienced yield losses, leading to 3.5 t ha-1 per season.
Yield site specificity for ± mineral N treatments was stonger than for organic resource treatments, e.g. the clayey
site in central Kenya in the end showed no yield differences between ± N, except for the 1.2 t C ha-1 yr-1 farmyard
manure treatment. Yet, farmyard manure plus mineral N consistently achieved highest yields of all organic
resource treatments at all sites and farmyard manure addition at 1.2 t C ha-1 yr-1 (about 5 t dry matter) was the
most N-efficient treatment.
Conclusions: At realistic application rates, maize yield in integrated soil fertility management is best sustained by
a combined application of farmyard manure and mineral N.
Implications: Mixed crop-livestock systems and a combined manure and mineral N application are key ingredients
for sustained productivity of smallholder systems in sub-Saharan Africa.
Description
Article
Keywords
ISFM, Maize yield potential, Residue quality, Food security, Sustainable intensification
Citation
Laub, M., Corbeels, M., Ndungu, S. M., Mucheru-Muna, M. W., Mugendi, D., Necpalova, M., ... & Six, J. (2023). Combining manure with mineral N fertilizer maintains maize yields: Evidence from four long-term experiments in Kenya. Field Crops Research, 291, 108788.