THE EFFECTS OF CONVENTIONAL TILLAGE TECHNIQUES ON SOME SOIL AND CROP PARAMETERS

Abstract

This work was carried out at Akure, latitude 7°. 5' N and longitude 5°. 10' E in the rain forest zone of Nigeria on soil type classified as alfisol to determine the effects of conventional tillage techniques on soil and crop parameters. Maize was used as the indicator crop. Soil parameters measured include 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, stem diameter, time taken before emergence and total emergence. The tillage treatments 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 using maize as an indicator crop. The effects of cultivation on the soil temperature, moisture retention, total porosity appear insignificant at the 95% confidence interval. But the soil density was significantly altered by the tillage treatments used. The total cost and gross margin of each tillage system used was also determined with an assumed constant yield of 2 tons per hectare at N17,000.00 per ton for all tillage treatments. Experimental results of all measured data established the superiority of one disc ploughing. over the other treatments. ANOVA results indicated that P.0.05 for 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 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 although results [rom statistical analysis XI showed that the total emergence was not significant. This trend of insignificant result was also observed for the measured stem diameter. The least root system both in number and length was observed on the zero tillage plots. The emergence force exerted by seedlings was significantly affected by tillage. Measured values of seedling emergence force, decreased from a maximum of 10.63 kN at the zero tillage plots to 8.96 kN for plots ploughed, harrowed and ridged; Values recorded [or other treatments are 939.34 grams for single pass disc ploughing and 913.76 grams for one disc ploughing followed by disc harrowing.