Organic inputs and farmers' management strategies in millet fields of western Niger

Abstract

Research on soil fertility management in sub-Saharan Africa was criticized lately for largely ignoring farmers' management strategies and the underlying principles. To fill this gap of knowledge, detailed interviews were conducted with 108 farm households about their rationale in managing the soil fertility of 307 individual fields in the agro-pastoral village territory of Chikal in western Niger. To amplify the farmers' information on manuring and corralling practices, repeated measurements of applied amounts of manure were carried out within six 1-km 2 monitoring areas from February to October 1998.The interviews revealed that only 2% of the fields were completely fallowed for a period of 1 -15 years, but 40% of the fields were at least partially fallowed. Mulching of crop residues was mainly practiced to fight wind erosion but was restricted to 36% of the surveyed fields given the alternative use of straw as livestock feed. Manure application and livestock corralling, as most effective tools to enhance soil fertility, were targeted to less than 30% of the surveyed fields. The application of complete fallow and manuring and corralling practices were strongly related to the households' endowment with resources, especially with land and livestock. Within particular fields, measures were mainly applied to spots of poor soil fertility, while the restoration of the productivity of hard pans was of secondary importance. Given the limited spatial coverage of indigenous soil fertility measures and their strong dependence on farmers' wealth, supplementary strategies to restrict the decline of soil fertility in the drought prone areas of Niger with their heavily weathered soils are needed. D

Beyond adding up inputs and outputs: process assessment and upscaling in modelling nutrient flows

“…However, even at higher faecal N-contents, undigested cell walls in faeces were supposed to be responsible for the observed temporary immobilization of mineral soil nitrogen ͑De Ridder and Van Keulen 1990;Powell et al 1999͒. Allowance for seasonal differences in the decomposition and mineralisation of applied organic matter must also be made when considering an intermediate time scale: the disappearance of manure is faster during the wet and the cool dry season than during the hot dry season, and is affected by soil temperature, rainfall and soil moisture ͑Somda et al Esse et al 2001;Schlecht and Buerkert 2004͒. Due to the manifold factors accelerating or decelerating manure decomposition, Somda et al ͑1995͒ were concerned about the uncertain timing of nutrient release. On the other hand, Powell et al ͑1999͒ welcomed the initial fixation of a certain portion of mineral N in the coarse SOM fraction after mulching or manuring, and suggested that the subsequent mineralisation would synchronize N-release with plant demand.…”

“…Manure accumulating at the homestead overnight is mixed with feed residues and household waste and transported to selected fields ͑Harris 1998; Schlecht and Buerkert 2004͒. Alternatively, corralling own or contracted livestock on the selected fields reduces labour and costs for transport and, through the direct recycling of faeces and urine to the targeted spot also reduces losses of nutrients, particularly nitrogen ͑Powell et al Hoffmann et al 2001;Schlecht and Buerkert 2004͒. Across five village territories in Western Niger, herds of approximately 25-60 animals were reported to spend between 15 and 46 nights on one field, thereby depositing 3.4-15.5 t ha -1 of faecal dry matter in the case of cattle and 1.3-7.2 t ha -1 in the case of small ruminants ͑Schlecht et al 2004͒.…”

“Fallow Band System,” a land management practice for controlling desertification and improving crop production in the Sahel, West Africa. 1. Effectiveness in desertification control and soil fertility improvement

“…However, 500-1000 kg ha À1 of post-harvest millet was not always effective in reducing soil flux. Although mulching with a large quantity of post-harvest millet residue is effective, application of 1500 to 2000 kg ha À1 is not realistic in the Sahel because the productivity of very sandy soils is too low and millet residue is extensively used as animal feed, fuel, and constructing material (Lamers and Feil 1993;Michels et al 1995b;Schlecht and Buerkert 2004).…”

“…This does not mean that farmers are ignorant of wind-erosion problems. Studies in Niger showed that most farmers recognize the severe damage caused by wind erosion, are aware of wind erosion control techniques, and many have even tried to apply one or several of these techniques (Taylor-Powell 1991;Sterk and Haigis 1998;Bielders et al 2001;Schlecht and Buerkert 2004). The main reason for non-adoption may be that developers and/or extension workers of these techniques did not give sufficient attention to their practicality for farmers.…”

Soil water crop modeling for decision support in millet-based systems in the Sahel: a challenge

“…So little crop residues are left on farms. Schlecht and Buerkert (2004) found in a recent survey in Chikal territory, southwestern Niger that mulching of crop residues was mainly practiced to fight wind erosion but was restricted to 36% of 307 individual farmers' fields given the alternative uses of straw. Quantities of stover found on farms in the Sahel before millet sowing are less than 800 kg ha -1 and mostly inadequate for effective mulching (Baidu-Forson, 1995).…”