Vetiver Seedlings Multiplication in Rice Husk Amended Soil and Crops Performance on Erosion-Prone Hillside under Vetiver Buffer Strips

Abstract

Vetiver buffer strips hold back soil on cultivated hillsides. A major constraint in their adoption is the low availability of seedlings for the establishment of buffer strips. Two experiments were conducted. In the fi rst, vetiver grass strip spacing (VGSS) at 5, 15, 25 m and farmers’ practice (FP) (no soil conservation measures used) were established as treatments on erosion plots sited on a cultivated hillside with a view to identifying the VGSS that would best increase crop yields. In the second experiment, 0, 25, 33.33, 41.67 and 50 t.ha-1 of rice husk were applied as soil organic nutrient enhancer to identify the rice husk rate that would maximize vetiver seedling multiplication on degraded soil. A traditional crop mixture of maize and cassava was introduced on mounds. Maize grain yield was signifi cantly infl uenced by VGSS and FP. Maize yields were 18.7, 8.7 and 11.6% higher on VGSS at 5, 15 and 25 m, respectively than on the FP plot. Maize dry matter accumulation between the VGSS and FP plots were signifi cantly different. Fresh cassava tuber yields were signifi cantly infl uenced by VGSS. Fresh cassava tuber yields were; 36.6, 12.2 and 13.2% higher on the VGSS at 5, 15, and 25 m, respectively, than on FP. The signifi cant benefi cial effect of VGSS in increasing crop yields on the cultivated hillside was evident. The farmer’s fi eld soil used for the vetiver multiplication was degraded having a sand fraction of 886 g.kg-1 of soil and a clay fraction of 40 g.kg-1. The soil was naturally very low in calcium and effective cation exchange capacity, low in organic carbon, nitrogen, magnesium and sodium and medium in potassium. Plant nutrient analysis of the rice husk used in amending the soil showed that it was high in available phosphorus and potassium, and medium in organic carbon and nitrogen. Vetiver tillers increased with the application rate of rice husk. A rice husk rate at 33.33 t.ha-1 could be the optimum rate of application as there was no signifi cant tiller increase beyond this rate.