Economic optimization of integrated soil fertility management strategies for maize-based production systems:a case study of smallholder farm typologies in central Kenya
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Date
2006-05Author
Macharia, John M
Type
ThesisLanguage
enMetadata
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In recent years, intensive cultivation with inadequate nutrient replenishment has widely been practised in many parts of sub-Saharan Africa. This land-use system has led to massive soil degradation and declining per capita food production. Consequent hunger, malnutrition and poverty have escalated. At the same time structural adjustment programs have eliminated all public farm-support initiatives leading to depressed usage of inorganic fertilizers. This has made prospects of achieving millennium development goals by the year 2015 increasingly challenging.
The major objective of this study was to develop optimal farm plans for profit maximization and food self-sufficiency in maize-based production systems of central Kenya under different soil fertility management (SFM) practices. The study was undertaken in Kariti and Mukanduini sites in Maragwa and Kirinyaga Districts respectively in 2003/4. Mann-Whitney (U) test was applied to verify whether or not there were significant differences between farmers classifications based on their SFM status and wealth endowment. Analysis of variance (ANOVA) was employed to test for soil fertility gradients between smallholder actual farm plans while benefit-cost ratio was used for ranking of different SFM technologies from on-farm trials. Finally, optimal farm plans for each farm typology were developed using linear programming.
The calculated ZaJ2 values were less than observed ZaJ2 values. The null hypothesis "that there is no significant difference (p < 0.05) between smallholders' SFM status and wealth endowment classification" was not rejected. ANOV A depicted significant differences (P < 0.05) in organic carbon, total nitrogen and available phosphorus between different classes. These parameters served as technical indicators of soil quality and were used to verify fanners' classification previously done using local indicators of soil quality. Carbon ranged between 1.65 - 2.24 percent and between 1.39 - 1.59 percent in Kariti and Mukanduini respectively, Nitrogen ranged between 0.11 - 0.15 percent and between 0.07 - 0.10 percent in Kariti and Mukanduini
respectively while available phosphorus ranged between 33 - 70 ppm and between 441 - 650 ppm in Kariti and Mukanduini respectively. Technical indicators of soil quality confirmed previous ranking of farmers into three farm typologies: Class I (good soil fertility managers), Class II (average soil fertility managers) and Class III (poor soil fertility managers).
From 15 different SFM technologies tested in on-farm demonstrations, the best three were identified in terms of benefit-cost ratios. These were Manure (5 tons/ha) + Fertilizer (60 kg N/ha) , Manure (5 tons/ha) + Fertilizer (40 kg N/ha) and Manure (5 tons/ha) + Fertilizer (20 kg N/ha). For profit maximization and household food security, bananas and tomatoes took all the land above self-sufficiency in the optimal farm plans in Kariti and Mukanduini respectively. Total gross margin in class I increased from Ksh. 20818 in actual farm plans to Ksh. 133989 in optimal farm plans in Kariti and from Ksh. 324119 in actual farm plans to Ksh. 994982 in optimal farm plans in Mukanduini. In class II, total gross margins increased from Ksh 5377 in actual farm plans to Ksh 97714 in optimal farm plans in Kariti and from Ksh 93784 in actual farm plans to Ksh 165719 in optimal farm plans in Mukanduini. In class III, total gross margin increased from Ksh -4372 in actual farm plans to Ksh 63691 in optimal farm plans in Kariti and from Ksh 23845 in actual farm plans to Ksh 200210 in optimal farm plans in Mukanduini.
In conclusion, wealthy farmers were also found to be good soil fertility managers. It was also established that all smallholders' farm plans were inefficient in resource allocation leading to low food production and farm income. The optimum level of application of nitrogen for maize production was found to be Manure (5 tons/ha) + Fertilizer (60 kg N/ha). For profit maximization and food self-sufficiency, all land over and above food self-sufficiency requirements should be allocated to banana and tomato production in Kariti and Mukanduini respectively. However, it is important to note that these recommendations are based on data collected for two seasons only. So such recommendations are not without limitations.
Citation
Masters thesis University of Nairobi (2006)Publisher
University of Nairobi. Department of Agricultural Economics
Description
Degree of Master of Science in Agricultural Economics