Effects of Conventional Tillage on Some Soil Properties, Root Growth and Seed Emergence
The experiment work was carried out at Akure, latitude 7, 5’ and longitude 5, 10’ E in the rain forest zone of Nigeria on soil type classified as alfisol. Maize was used as the indicator crop. Soil parameters measured included bulk density, moisture retention, soil temperature, porosity aggregate stability and soil shear strength while crop parameters measured include root length and number of main roots, and crop emergence. The tillage treatment used included zero tillage (ZT), one ploughing (PL), one ploughing followed by harrowing (PH) and ploughing, harrowing and ridging in sequence (PHR). All operations are single pass. The result provided enough evidence that the soil structural condition as modified during tillage, affects the soil physical properties and some crop properties. The effects of cultivation on the soil temperature, moisture retention appear insignificant at the 95% confidence interval, but the soil density was significantly altered by the tillage treatment used. Experimental results of all measured data established the superiority of one disc ploughing over the other treatments. ANOVA results indicated that most of the physical properties are statistically significant at 95 % confidence level except soil density and the mean weight diameter (MWD) by dry and wet sieving. Analysis of results also revealed that shear strength of the soil decreased with tillage treatments. It was found that emergence was earliest in treatment three and lowest in treatment four, decreasing directly with increasing soil strength. Similarly, result of statistical analysis showed that total emergence was not significant although the emergence force exerted by seedling was significantly affected by tillage. It decreased from a maximum of 10.63kN at the zero tillage plots to 8.85kN for plots ploughed, harrowed and ridged. Values recorded for other treatments are 9.22 kN for disc ploughing and 8.96 kN for one disc ploughing followed by disc harrowing. The least root system both in number and length was observed on the zero tillage plots.