A long term experiment at ICRISAT’s Sadore research station with Ziziphus mauritania (Pomme du Sahel) trees showed pearl millet yields rising by up to 41% in low input conditions. The observations led researchers to recommend ziziphus trees at 80 plants per hectare and helped show how smallholder farmers in Niger’s drylands can increase productivity and income potential two to threefold from both mono-cropping and intercropping systems with agroforestry.
The experiment, which started in 2004 and featured agronomic work conducted from 2015-2018, involved cultivating pearl millet and cowpea as mono crop and inter-crop in four input scenarios– without organic fertilizer or manure, with Nitrogen, Phosphorous and Potassium (NPK), with manure and with both NPK and manure. Each of these four scenarios for both mono-crop and intercrop was replicated in two blocks– with and without ziziphus trees. The experiment’s results were recently published in Agriculture, Ecosystems and Environment.
“Smallholder farmers in the West African Sahel farm on landscapes where poor soils and frequent droughts threaten their food security,” said Dr Bado, the study’s lead author. “They have limited resources to invest on inputs. The experiment we conducted aimed to determine what hardy and income producing trees like ziziphus can do in such systems. To draw conclusions from the experiment that would mirror on-ground conditions, we grouped the observations in two.”
Accordingly, the first group is the low-input group, where no fertilizer was used or only manure was used in the experimental plots. The second is the moderate input group, where either NPK or a combination of NPK and manure was used.
In the first group, pearl millet monocrop plots with ziziphus trees recorded a mean yield increase of 41% without fertilizer and 10% with manure, when compared to plots with the same nutrient inputs but without the trees.
Contrastingly, in the second group, ziziphus trees did not increase mean yields (in some cases decreased yields) in plots where NPK and NPK-manure was applied. Similar observations were made in the intercropping plots.
“In the low-input group, ziziphus trees improved water use efficiency of pearl millet and millet-cowpea cropping systems. However, where some fertilizer and manure was applied, the trees did not affect water-use efficiency or yields of crops. But, the income was higher due to the fruit output,” said Dr Anthony Whitbread, Director for ISD Research Program at ICRISAT and one of the study’s authors.
“Increased nutrient supply in the second group meant more competition for light and water in these plots. This observation requires more research to determine the optimal arrangements and density of trees and crops depending on fertility inputs,” he explained.
The study’s three authors including Mr Laminou Sanoussi, Scientific Officer at ICRISAT-Niger, noted that ziziphus trees led to maintaining soil organic carbon and nitrogen levels. The increased crop yield and products of ziziphus agroforestry increased incomes up to three times during the experiment.
Since the 1980’s, ICRISAT has been promoting the technique of microdosing– direct application of small quantities of fertilizer at the time of planting- in combination with water harvesting practices. These low-cost interventions have been shown to maximize the efficiency of input use via increased yields and incomes. When used with agroforestry, these practices can help farmers in the Sahel improve soil fertility, generate multiple income streams and make their livelihoods resilient.
The study was taken up under an EU and IFAD funded project. The study’s authors partnered with Dr Fergus Sinclair and Dr Leigh Ann Winowiecki from World Agroforestry (ICRAF).