Retention of macronutrients in a sandy soil amended with vermiculite under Tanzanian field conditions
2010
Marwa, E. M.M. | Meharg, A. A. | Rice, C. M.
The study assessed the ability of vermiculite to enhance the retention of extractable nitrogen (N), phosphorus (P), and potassium (K) in arable Tanzanian soils. Raw and expanded vermiculites pre-heated at 600 oC were mixed with a sandy soil in varying amounts. Inorganic fertilizers N, P and K were added to the soil-vermiculite mixes and buried at 0-15 and 15-30 cm depth in litter bags for three months during the rainy season. After that period, extractable N, P and K retained in the mixes were determined. The result showed that less than 10% of the applied N was retained whereas for K it was 26-48%. Phosphorus was highly retained and in part fertilized from vermiculite over the control. The maximum extractable fertilizer P retained in soil amended with expanded vermiculite was 78%, whereas in soil with raw vermiculite it was 141%, suggesting that vermiculite also retains soil P mineralized over the course of the experiment. More retention of N, P and K occurred at 15-30 cm than at 0-15 cm and increased with the amount of vermiculite mixed with the soil. Thus, use of vermiculite enhances soil productivity by retaining extractable essential macronutrients which could be used for crop production.
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