Comparison of tillage practices on the change of soil properties and cassava yiled

Abstract

A study on comparison of tillage practices on the change of soil properties and cassava yield was conducted in the area of Tapioca Development Institute, Huai Bong subdistrict, Dankhunthod District, Nakhon Ratchasima province to investigate the impact of tillage types on soil properties and yield of cassava Huai Bong 80 variety. Randomized Complete Block Design was used for the experiment, employing four treatments with four replications as follow; three- followed by seven-disc plough with no ridge, three- followed by seven-disc plough and ridging, mouldboard followed by seven-disc plough with no ridge, and only seven-disc plough with no ridge. Representative soil in the experimental area was classified as Kanhaplic Haplustult, having sandy loam texture, high bulk density (1.2-1.8 Mg m-3), slow saturated hydraulic conductivity (lower than 1 cm hr-1), and low fertility level both in top and subsoil layers. Result showed that there was no statistical difference in obtained fresh tuber yield (harvested at approximately 10 months of age) among treatments. The use of three-disc followed by seven-disc for land preparation with cassava grown on the ridge tended the give the highest yield of 2.61 tonne rai-1. Using mouldboard followed by seven-disc had a tendency of giving the highest above ground biomass (leave, stem base and stem) in total of 2.45 tonne rai-1. Statistically, the starch percentage of cassava tuber gained from that of the highest one (26%) was significantly lower than that of other treatments (30-31%). Changes of soil properties as affected by tillage practices at depths between 0-20 and 20-40 cm within 20 and 40 cm from the plant indicated that a single plough using seven-disc was likely to have greater amounts of OM, total N, available P and K left in soils than to do other treatments. It, however, caused slight compaction and slow saturated hydraulic conductivity, particularly in the topsoil layer while more trafficking as such a treatment using three- followed by seven-disc and ridging showed the contrary in the context of these physical properties. This is only one year experiment therefore the result might not be clearly conclusive. Longer term trial is recommended for more reliable outcome.