Controlling soil erosion in smallholder potato farming systems using legume intercrops
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Date
2019
Authors
Nyawade, Shadrack O.
Gachene, Charles K. K.
Karanja, Nancy
Gitari, Harun I.
Schulte-Geldermann, Elmar
Parker, Monica L.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier B.V.
Abstract
Soil and nutrient losses due to soil erosion are pronounced in potato growing areas of East Africa due largely to
the rugged topography and high soil disturbance associated with potato cultivation. This study intercropped potato
(SolanumtuberosumL.)with three grain legumes: lablab bean (Lablab purperous L.), garden pea (Pisumsativa
L.) and climber bean(Phaseolus vulgaris L.) in runoff plots and assessed their impact on soil and nutrient losses in
central Kenya highlands. Bare plots and sole potato stands were included as controls. Vegetal cover was
measured at different potato growth stages while runoff and soil loss were quantified at every runoff generating
event and used for nutrient analyses. Yieldswere expressed as potato equivalents (PEY) at the end of each season.
Mean cumulative sediment yield decreased from 169 t/ ha in sole potato plots to 50–83 t/ ha in potato-legume
intercropping, representing a reduction of 51–70%. The eroded sediment exported in large quantity
the SOC (16.6–39.5 kg C ha−1 yr−1), N (5.5–29.8 kg N ha−1 yr−1), P (3.9–16.4 kg P ha−1 yr−1) and K (5.2–
14.6 kg K ha−1 yr−1) and were consistently higher in sole potato plots relative to potato-legume intercropping.
These losses occurred mainly at potato emergence following fertilizer application. Stronger associations of sediment
nutrient enrichments was found with the micro-aggregates (250–50 μm) than with themacro-aggregates
(N250 μm) pointing to the different degree of nutrient mobilization and distribution in eroded sediment. The PEY
were significantly greater in potato-lablab bean systemthan in sole potato,while intercroppingwith garden pea
and climber bean showed similar PEY to that of sole potato, suggesting that potato-lablab system may be preferred
by the smallholder farmers. These results justify the need to intercrop potato with indeterminate legume
intercrops, a strategy that must be done in a way guaranteeing high yield stability to the smallholder farmers.
Description
Research Article
Keywords
Grain legume intercrops, HUMIC NITISOLS, Nutrient losses, Runoff, Soil erosion, Soil loss
Citation
Geoderma Regional 17 (2019) e00225