Abstract
Filter cake is one of the waste products from sugar mills; it is rarely used in maize production. Its potential as a soil amendment in maize production was investigated in the Middleveld ecological zone of Swaziland. Four levels of filter cake (0 kg ha-1; 10,000 kg ha-1; 20,000 kg ha-1; 40,000 kg ha-1) and 400 kg ha-1 of a compound fertilizer were studied using a randomized complete block design, replicated four times. Results showed that filter cake at 40,000 kg ha-1 significantly (P < 0.05) increased soil organic matter. Phosphorus level in 40,000 kg ha-1 of filter cake was 31.5 mg kg-1 greater than the commercial fertilizer treatment. There was a non-significant decrease in soil acidity (from pH 6.50, without filter cake, to 6.60 at 40,000 kg ha-1 filter cake). Except for Cu and B, other micronutrient concentrations showed significant (P < 0.05) increases with filter cake. Filter cake significantly (P < 0.05) increased maize yield from 3,731.8 kg ha-1 without filter cake, to 5,253.6 kg ha-1 with 40,000 kg ha-1 of filter cake. Yield with fertilizer (5,045.9 kg ha-1) was non-significantly lower (by 3.95%) than yield from the highest filter cake level. Application of filter cake at the rate of 40,000 kg ha-1 is recommended for maize. It is suggested that a long-term study be conducted to better understand the benefits of filter cake in relation to organic matter and mineral concentrations.
