Principles of Integrated Soil Fertility Management (ISFM)
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DESCRIPTIONPrinciples of Integrated Soil Fertility Management (ISFM). Africa Soil Health Consortium 2013. Introduction to ISFM as a concept. Objectives. Understand the history of soil fertility management Understand why ISFM is needed for smallholder farmers in sub-Saharan Africa - PowerPoint PPT Presentation
<ul><li><p>Principles of Integrated Soil Fertility Management (ISFM)</p><p>Africa Soil Health Consortium2013Introduction to ISFM as a concept</p></li><li><p>ObjectivesUnderstand the history of soil fertility managementUnderstand why ISFM is needed for smallholder farmers in sub-Saharan AfricaUnderstand the individual components of ISFM and their interactions with each otherUnderstand the variability between farms and the need for local adaptation of nutrient input recommendationsUnderstand the concept of agronomic efficiencyUnderstand the concept of economic efficiency </p></li><li><p>History of soil fertility management2000s1990s1980s1960s and 1970sApproach: external input use</p><p>Fertilizer: +++Organic inputs: - </p><p>Limited success, shortfalls in infrastructure and farming systems</p><p>Approach: organic input use</p><p>Fertilizer: -Organic inputs: +++</p><p>Limited adoption, organic matter production requires land, labour and/or livestockApproach: organic input use & fertilizer</p><p>Fertilizer: +Organic inputs: +++</p><p>Localized adoption around specific crops</p><p>Approach: integrated soil fertility management</p><p>Fertilizer: ++Organic inputs: ++</p><p>Goal of large scale adoption</p></li><li><p>Focus on mineral fertilizerAdding nutrients: The Green RevolutionA success in Asia and Latin AmericaExternal input use (mineral fertilizers & lime)Improved varietiesIrrigation</p><p>A disappointment in sub-Saharan AfricaFertilizer is too costlyFertilizer use is uneconomic in poorly responsive environmentsFertilizer recommendations were not tailored to farmers specific circumstancesHeterogeneous soil fertilityThe farmers social and economic situation and goals</p></li><li><p>Focus on organic resourcesConserving nutrients: through compost and manureRecycling nutrients : through deep rooting treesAdding nitrogen: through biological N2 fixation (BNF) by leguminous cover crops, trees, shrubs and grain legumes</p><p>Disadvantages:Quality of organic resources is often poorQuantity of manure or organic resources is not sufficient Competing uses for plant residuesOrganic materials are bulky and costly to store, transport and apply Adoption and suitability of leguminous cover crops is limited by (1) high labour requirements(4) drought and low soil pH limit BNF (2) only N can be supplied (5) lack of useable yield (grain (3) availability of other nutrients (e.g. P) legumes excepted) need to be sufficient for effective BNF </p></li><li><p>Nutrients from outside the farm are needed!Need to integrate fertilizer and organic resources!When unsufficient nutrients are added to maintain soil fertility: downward spiral into a poverty trap</p></li><li><p>Integrated Soil Fertility ManagementA set of soil fertility management practices that necessarily include the use of fertilizer, organic inputs and improved germplasm combined with the knowledge on how to adapt these practices to local conditions, aiming at optimizing agronomic use efficiency of the applied nutrients and improving crop productivity. All inputs need to be managed following sound agronomic and economic principles.</p><p>Yield = G (genotype) x E (environment) x M (management)</p></li><li><p>Principles of production ecologyYield = G (genotype) x E (environment) x M (management)</p><p>YP = G x E</p><p>YW = G x E x M (water)</p><p>YA = G x E x M (water) x M (nutrients, pesticides, weeding, etc)Defining factorsLimiting factorsReducing factors</p></li><li><p>Components of ISFMYield = G (genotype) x E (environment) x M (management)</p><p>Seeds should be adapted in terms ofResponsiveness to nutrients (M)Adaptation to the local environment (E)Resistance to pests and diseases (E)</p></li><li><p>Components of ISFMYield = G (genotype) x E (environment) x M (management)</p><p>Mineral Fertilizers:Supplement recycled or added nutrients from organic sourcesContain essential nutrients in a form readily available for plant uptake.Organic inputs:Source of nutrients, including nutrients not contained in mineral fertilizersReplenish soil organic matterIncrease the crop response to mineral fertilizerImprove availability of phosphorus for plant uptakeRegulate soil chemical and physical propertiesCreate a better rooting environment due to the improvemnet of the soil structureImprove the soils capacity to store moistureMaintain the biodiversity in the soil</p></li><li><p>Positive interaction: fertilizer organic matterWithout organic matterWith organic matterABC</p></li><li><p>Long term effect of fertilizer and crop residues on millet grain yield in Sadore, NigeriaPositive interaction: fertilizer organic matter</p></li><li><p>ExerciseEffect of fertilizer (60 kg N, 13 kg P and 25 kg K/ha from NPK (17:17:17 and urea) on grain yield of 2 local and 2 improved maize varieties in south Kivu, DR Congo.1. What can you conclude from this figure?</p><p>2. What do you still have to take into account before making recommendations based on this figure?</p></li><li><p>2. Highest yields with fertilized hybdrids3. Yields more than doubled when both fertilizer and improved germplasm was used4. Yield from unfertilized BH540 was slightly higher than fertilized local varieties1. All varieties had larger yields when fertilizer was applied</p></li><li><p>Local adaptationVariability between farmsVariability between farmsGoals and objectivesImportance of off-farm incomeAmount of production resources available to invest in the farmLandLabour Animal manureCrop residuesCashTittonell et al. (2008)</p></li><li><p>Local adaptationVariability between fieldsSoil fertility gradients within farms: Fertile home fieldsDegraded outfields</p></li><li><p>Low or no response:Fertile in-fields, due to high amounts of nutrients applied in the pastDegraded soilsWeed infested fieldsResponsive (in-field)</p><p>Less-responsive(outfield, couch grass infestation)</p><p>Unresponsive(degraded soil)Unresponsive(degraded soil)Responsive (in-field)</p><p>Less-responsive(outfield, couch grass infestation)</p></li><li><p>Variable responses to nutrient inputsTittonell and Giller (2013)</p></li><li><p>The response to seed and fertilizer inputs is large in responsive soilsThe response to seed and fertilizer inputs is small in unresponsive soils Organic resources are needed to make efficient use of fertilizer and improved seeds in unresponsive soils</p></li><li><p>Agronomic efficiency (AE)YF: Yield in treatment with nutrient applicationYC: Yield in control treatmentXappl: the amount of nutrient X applied (kg nutrient/ha) </p><p>The amount of additional yield obtained per kg nutrient applied</p><p>AE = (YF-FC) / Xappl</p></li><li><p>Increasing AETo increase AE (and yield) at a particular fertilizer application rate:</p><p>Plant the crop at the right planting densityApply fertilizer at the right time Apply fertilizer in the right place Apply fertilizer in several split applications</p></li><li><p>Sound agronomic principlesMaximum return to investments and high AE need good crop management with:Appropriate varietiesAppropriate land preparationSpacingPlanting dates and practicesWeedingPest and disease management practicesAppropriate intercropping arrangements</p></li><li><p>Sound economic principlesComparing the value of additional yield with the costs of the inputs required </p></li><li><p>ISFM From poverty traps towards an African Green Revolution?</p></li><li><p>Exercise1. Calculate the agronomic efficiency:applying 100 kg fertilizer per haapplying 200 kg fertilizer per ha</p><p>2. Calculate the value:cost ratios for:Increasing yields from point B to point CIncreasing yields from point C to point D</p><p>3. Is it economically sound to increase yields up to point E with the use of fertilizer?</p><p>4. What happens to the maximum economic yield when the price of fertilizer increases?</p><p>CoordinatesPoint A: (0, 500)Point B: (50, 2300)Point C: (100, 3000)Point D: (150, 3300)Point E: (200, 3380)PricesThe price of N fertilizer is 1 US$/kgYield can be sold for 0.5 US$/kg</p></li><li><p>Exercise: From poverty traps towards an African Green Revolution?</p><p>Sounds perfect!</p><p>But: how easy is it to reverse the downward spiral into an upward spiral?</p><p>Exercise: Think about two factors that could constrain this process.</p></li><li><p>Exercise: From poverty traps towards an African Green Revolution?</p><p>The problems with availability of fertilizer and organic inputs from the 1970s and 1980s have not yet overcome.It takes several years for a degraded soil to become productive and responsive again. How does the farmer finance the rehabilititation of his/her field?Storing and marketing produce is often problematic so the foreseen impacts in terms of increased income and food security cannot be taken for granted.ISFM is very important, but interventions in the political and economic environment are needed to make ISFM work! </p><p>*Initially, population sizes were small and land was abundant. Farmers maintained soil fertility by never cultivating a field for a long period of time; they practiced shifting cultivation. Fields were openend up and cultivated for one to several years and left to regenerate for a rather long period. There was no need for external inputs. However, when the human population increased, land became scarce and fallow times were shortened and eventually dissappeared. In some countries with low population densities, shifting cultivation is still practiced, but in most countries with high population densities, continuous cropping has become the norm. Without a fallow or regeneration period, the need for external nutrient inputs to maintain soil fertility emerged. Since the 1960s, the understanding about nutrient management in cropping systems has developed and changed substantially.</p><p>-click- In the 1960s and 1970s major emphasis was placed on the use of mineral fertilizer to achieve proper crop nutrition and improved crop yields. Mineral fertilizer alone was thought to be sufficient to improve and sustain yield. Organic resources only played a minimal role. However, there was only limited success with this approach, partly because of the problems with fertilizer access in SSA during that period. </p><p>-click- In the 1980s mineral fertilizers only played a very limited role and strong emphasis was given to the use of organic resources as the main source of nutrients. However, adoption of use of organic resources was also limited due land and labour constraints, and because livestock ownership was not widespread.</p><p>-click- Up to now, much research has shown the importance of combining the use of mineral fertilizers and organic resources, which is the essence of ISFM. In the 1990s organic resources still were the major entry point to soil fertility improvement, partly to supply nutrients, and partly to serve other functions than nutrient supply. Mineral fertilizer was used as a supplementary but essential input to alleviate the main nutrient constraints. </p><p>-click- In the 2000s, fertilizers are considered the major entry point to increase yield. The combinatiom of organic resources and mineral fertilizer can improve the use efficiency of fertilizer. Another important aspect of integrated soil fertility management is that recommendations for mineral fertilizer and organic resourced are locally adapted, and therefore there is the goal of large-scale adoption.</p><p>The next couple of slides go into more detail on the focus on mineral fertilizer versus the focus on organic resources.</p><p>*A success in Asia and Latin America - Large increases in crop yields since the 1960s</p><p>A dissapointment in sub-Saharan Africa Research has shown that mineral fertilizer has the potential to enhance crop production also in SSA, but there has not been a green revolution like in Asia. So, why not?Many farmers thought fertilizer is/was too costly or even unaffordable. Fertilizer is indeed more costly in most countries in SSA than in any other continent in the world. This is mainly caused by a lack of efficient fertilizer market infrastructure and poor transport networks. In addition, in many cases, fertilizer use was uneconomic due to poor performance of crops and therefore poor responses to fertilizer in poorly responsive environments. Poorly responsive environments include environments where top soil has been lost (erosion), soils where stocks of nutrients other than supplied by the fertilizer have become insufficient to maintain proper crop growth or soils which are very acidic. Drought and weed infestation also can make fertilizer use uneconomic.Part of the problem was also that fertilizer recommendations were not tailored to farmers specific circumstances. For example, in densely populated areas with limited access to organic resources, soil fertility varies widely within each farm. There may be more fertile fields close to the farmers house and less fertile soils in more distant fields. These fields need different fertilizer recommendations to make fertilizer use economically sound.Also, the farmers social and economic situation needs to be taken into account when devising fertilizer recommendations. For example, market-oriented farmers are strongly engaged in the production of crop products for sale. Other farmers, who are often less well endowed with production resources like land, labour and cash, are less market oriented and instead seek to ensure food self-sufficiency.</p><p>*As a response to the problems that occured with mineral fertilizer, as we just discussed, low input strategies became the trend. </p><p>In the low input approach, the focus is on conserving nutrients (through compost and manure), recycling nutrients (through deep rooting trees) and adding nitrogen though biological nitrogen fixation. With the conservation and recycling approaches it is assumed that there are sufficient organic resources available to improve the productivity and sustain the natural base of the system.</p><p>However, in many cases, the nutrients provided by those low input strategies are in fact not sufficient to meet the nutrient requirements of the plants and productivity cannot be sustained over the longer term.In the first place, the quality of organic resources is often poor, with low nutrient content or poor nutrient release characteristics. Because of the poor quality, large quantities are needed to provide sufficient nutrients.The quantity of available manure or other organic resources is often not large enough. In addition to the total quantity available not being sufficient, when farmers rely on plant residues as organic nutrient source, trade-offs have to be made between using the residues for compost or using (or selling) them as feed for livestock.The amount of organic resources applied is often also restricted by the available labour, because organic materials are bulky, and therefore costly to store, transport and apply.The adoption of practices that add nitrogen through BNF, such as leguminous cover crops, is also low because (1) it is labour intensive, (2) only N can be supplied by BNF, (3) the fixation of N depends on the availability of other nutrients (such as P) and (4) factors such as pH and drought. When P is not sufficiently avaiable, or when the pH of the soil is too low, legumes will not effectivly fix N and will also not add N to the system. Another disadvantage of using legumes as organic resource is that, (5) except when grain legumes are grown, there is no useable yield. </p><p>*Figure: The downward spiral to the povertry trap for farm systems where the nutrients added are insufficient to maintain soil fertility.</p><p>Conserving and recycling nutrie...</p></li></ul>
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