GUEST COLUMNSOIL MANAGEMENTMartinKoinangeResearchhas reportedanincreasein maizegrain from1 to 2.4 tonper hectareunder ISFMsystemscomparedto the soleuse of mineralfertilizers34HUSTLE EAST AFRICAHow Soil FertilityManagement Could EnhanceFood SecurityLow crop productivity is a perennial problemin Kenya among smallholder farms. It’sa direct result of various unaddressedfactors which include; the exponentialdecline in soil fertility, high fertilizer costsand the intensification of agriculture coupled withthe reduction in farm sizes. In addition, chemicalfertilizers do not directly improve the soil’s physicalstructure or enhance its biological activity. They areoften insufficient when it comes to maintaining soil.Based on these major limitations to crop production,research on soil fertility, crop nutrition andsocioeconomics in smallholder farming systems hasbeen done in Sub-Saharan Africa (SSA) and shownthat combined interventions on fertilizer and organicinputs coupled by use of improved crop varietiesare a prerequisite for achieving high and sustainableyields. Integrated Soil Fertility Management(ISFM) builds on this notion and is defined as: a setof soil fertility management practices that necessarilyinclude the use of fertilizer, organic inputs, andimproved germplasm combined with the knowledgeto adapt these practices to local conditionswith the aim of maximizing the agronomic useefficiency of the applied nutrients and improvingcrop productivity.The use of improved germplasm enhances yieldpotentials as well as combat pests and diseases.Mineral fertilizer-use in ISFM targets the formulation,placement, rate and timing of inorganicnutrient inputs. Integration of different fertilizerplacement and/or rate practices such as micro-dosing,deep placement, banding, and harmonizing ofinputs with rainfall and nutrient demands enhancenutrient uptake and productivity of crops. Interventionson organic resource management targets thereturn of crop residues and use of manure, compostand other types of organic wastes. Additionally,crop rotation or intercropping with legumes anduse of beneficial soil micro-organisms make an integralpart of ISFM. The last entry point of ISFM dealswith any other amendments that may be neededto reduce the limitations to productivity such ascorrection of soil acidity, micronutrient deficiency,erosion, soil compaction or pests and diseases controlmeasures. On the other hand, local adaptationof nutrient management refers to specific decision-makingprocesses in relation to the allocationof agro-inputs and management practices at thefarm level, thus recognizing production objectives,resource endowments, and farm-specific soil fertilityconditions.The combined application of mineral fertilizerand organic inputs is practical to smallholderfarmers because; (i) both fertilizer and organicinputs are often in short supply in smallholderfarming systems due to limited affordability and/oraccessibility; (ii) both inputs contain varying combinationsof nutrients and/or carbon, thus addressingdifferent soil fertility-related constraints; and (iii)extra crop produce can often be observed due topositive interactions between fertilizer and organicinputs. ISFM fits well with small scale farmers dueto its wide applicability across different soil types,cropping systems and resources endowment.Research has reported an increase in maize grainfrom 1 to 2.4 ton per hectare under ISFM systemscompared to the sole use of mineral fertilizers. Thehigher productivity and yield stability achieved inthe ISFM system prove that the practices significantlystrengthen the resilience of crops to climatechange impacts. Additionally, soil organic carboncontent (an indicator of soil fertility) increases whenfertilizers and organic inputs are combined as comparedto when either is used solely.Despite the significant benefits of ISFM in foodsecurity, the adoption of practices in African smallholdersystems is usually low and incomplete dueto; high costs of input and poor produce trading,shortage of credit facilities for making initial investments,high cost and limited availability of labor,small land sizes, lack of information about the soilstatus and rainfall forecasts, scarcity of organicinputs and competition of crop residues with livestock.Regardless of these challenges, ISFM remainsthe most sustainable solution to food and nutritionalsecurity among smallholder farmers.
HUSTLE EAST AFRICA