EFFECT OF SITE-SPECIFIC FERTILIZER APPLICATION ON SELECTED SOIL PHYSICOCHEMICAL PROPERTIES AND MAIZE (Zea mays L.) YIELD IN MIKALANGO EXTENSION PLANNING AREA, SOUTHERN MALAWI

Abstract

Malawi’s economy is solely agricultural driven, yet the soils are continuously depleted of major nutrients threatening economic development, food and nutrition security. Besides poor agricultural practices, climate change is one of the major factors exacerbating soil and nutrient degradation in sub-Saharan Africa. Use of blanket fertilizer recommendations to nourish the depleted soils is worsening the situation as it often not matches with the requirement of the soil and maize, the country’s staple food crop, a situation which could further be contributing to N2O emissions from highly fertilized agricultural soils. This study assessed the effectiveness of site specific fertilizer application in improving soil fertility and maize yield in Mikalango EPA, southern Malawi in comparison with the current blanket fertilizers for maize. The experiment was set up in a randomized complete block design with 5 fertilizer treatments and 5 replications where one hybrid seed variety DKC 8033 was planted. Primary data was collected from soil laboratory results on selected soil physicochemical properties and observations on maize growth and yield components while climate data was collected from the Shire Valley Agriculture Development Division meteorological station. Analyses of variance using JMP SAS software version 14.0.0 were used to analyze the soil physicochemical properties, maize growth and yield components data. Mean separation was conducted using Turkey-Kramer HSD. The results indicated that there were significant differences between the fertilizer treatments in affecting soil physicochemical properties; pH (p<.0001*), N (p<.0001*), P (p<.0001*), S (p<.0001*) and Zn (p<.0001*) as well as maize growth and yield components Height (p<.0018), Leaf area index (p<.0028*), Leaf color (p<.0001*), Cob length (p<.0004*), Plant dry weight (p<.0001*) and Grain yield (p<0001*). The mean separation reports revealed that site-specific fertilizer was highly significantly different from the blanket fertilizers by increasing soil P (0.3%), S (24.2 ppm) and Zn (1.92 ppm) as well as maize dry weight (2.56 kg) and grain yield (7.03 mt ha-1 ) while it was also as effective as the national and mixed fertilizers in affecting the rest of the soil physicochemical properties and yield components more than manure which was the fourth most effective while control was the least effective. Furthermore, the site-specific fertilizer was the most cost effective with a higher net income of Mk3,243,000 ($3,243) than the blanket fertilizers when economic analysis was conducted. Therefore, it was concluded that site-specific fertilizer application was the most effective hence a potential synergy for simultaneously improving soil physicochemical properties, maize yield and reducing N2O emissions being soil specific. The study highly recommends scaling up of soil testing across the country in order to easily formulate site-specific fertilizer blends based on distinctive soil physicochemical properties and moving swiftly to enroll the blends into the government agricultural policies.