Groundnut response to calcium and phosphorus fertilizer rates in Tanzania

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My research focused on investigating the response of groundnut to inorganic sources of calcium (Ca) and phosphorus (P) with emphases on yield, fats and protein contents, as well as profitability of fertilizer in groundnut production at Sokoine University of Agriculture in Morogoro, Tanzania.

The study was conducted in Morogoro region, an area located at 525 m above sea level in Morogoro municipality. The area is situated at the foot of Uluguru mountain and the climate is predominantly sub-humid. The region is characterized by a bi-modal rainfall pattern, with short rains from November to December and long rains from March to May/June. The rainfall distribution is irregular and unreliable. The soil in this area is dominated by kaolinitic clay, which is well drained.

The main objective of the study was to identify appropriate fertilizer rates for calcium and phosphorus from inorganic sources for groundnut production. We used Di Ammonium Phosphate (DAP) as source of phosphorus, at 55 kg P ha-1. Locally produced Minjingu mazao was used as source of calcium, at 125 kg Ca ha-1.

The study results found that application of DAP significantly (P< 0.05) increased kernel yields, from 1,505 to 1,760 kg ha-1. An increase in pod yield was also observed, from 2,676 to 3,025 kg ha-1. A value cost ratio (VCR) of 2.2 was obtained with application of  DAP, compared to a VCR for Minjingu mazao of 0.3. For groundnut farmers, this implicates that application of DAP increases kernel and grain yields, hence profitability. Furthermore, Minjingu mazao did have significant (P< 0.05) effect on leaf area index, crop biomass, crop growth rate, biological yield, number of filled pods per plant and oil content. A net income of about $1,969 was accumulated with application of DAP, compared to $550 with calcium application.

Picture 1. Mr. Henry Nyuma displaying freshly harvested groundnut crops at Sokoine University of Agriculture

Results from this study reported increase in grain and pod yields due to application of DAP, hence profitability. However, further studies using different fertilizer rates and combinations of calcium and phosphorus might provide optimum fertilizer rates for groundnut production in Tanzania.

Henri Tamba Nyuma