Change in Soil Fertility and Beetroot Productivity after Single and Mixed Application of Basalt Dust, Poultry Manure and NPK 20-10-10 in Nkwen (Cameroon Volcanic Line)

This work aims to compare the effects of basalt dust, poultry manure and NPK 20-10-10, single and combined, on the growth and yield of beetroot (Beta vulgaris). Thus, fieldwork was preceded by land evaluation and standard laboratory soil analysis. A randomized complete block design (RCBD) on a 172.5 m2 experimental plot was used to investigate the effects of nine treatments: control soil (T0), T1 (5 tons ha-1 basalt dust), T2 (0.7 tons ha-1 NPK 20-10-10), T3 (20 tons ha-1 poultry manure), T4 (2.5 tons ha-1 basalt dust), T5 (0.35 tons ha-1 NPK 20-10-10 + 10 tons ha-1 poultry manure), T6 (10 tons ha-1 poultry manure + 2.5 tons ha-1 basalt dust), T7 (0.35 tons ha-1 NPK 20-10-10 + 2.5 tons ha-1 basalt dust) and T8 (0.25 tons ha-1 NPK 20-10-10 + 6.5 tons ha-1 poultry manure + 2.5 tons ha-1 basalt dust). The main results showed that land limitation was severe (N1), due to soil acidity, and potentially unsuitable for beetroot cultivation. The control (T0) was acidic (pH=4.8) but treatment raised the pH to 6.56, 6.76 and 4.91 for basalt dust, poultry manure and NPK 20-10-10, respectively. The yields were recorded in decreasing order as T3>T8> T6>T5>T7>T2 >T4>T1>T0. T1 had the highest capacity to provide nutrients to soils and to balance nutrient availability to plants. T3 alone boosted immediate productivity by improving soil acidity. The most economic treatment was T8 suggesting a reduction in chemical fertilizer input and importation and popularization of local natural fertilizers.