EFFECT OF TILLAGE METHODS ON SOIL PHYSICAL AND STRENGTH PROPERTIES UNDER AMARANTHUS HYBRIDUS PRODUCTION IN A SANDY-LOAM ENVIRONMENT

Amaranthus hybridus (African Spinach) production is a common vegetable in many southwestern parts of Nigeria. Many farmers grow it for its high source of protein and vitamins under different soil conditions without taking into consideration the tillage method that best gives the highest yield. A field study was conducted on a sandy loam soil in the National Centre for Agricultural Mechanization, Ilorin. Nigeria during the raining season of 2017 to investigate the effect of tillage methods on soil physical properties, penetration resistance and shear strength under Amaranthus hybridus production. The experiment was a completely randomized design with three replications. Tillage methods were disc plough (DP), disc harrow (DH), combination of disc plough and disc harrowing (DPH) and zero tillage (ZT). Soil physical parameters investigated during the growth stages of the crop were soil bulk density, soil moisture content, penetration resistance, shear stress and total porosity. Average bulk density for DP, DPH, DH and ZT were 1.33, 1.30, 1.25 and 1.50 g/cm3 respectively. Shear stress increased with depth in all the plots. Maximum values at the 14-21 cm depth were 132, 104, 166 and 16 mPa for DP, DPH, DH and ZT respectively. The average penetration resistance on the DP, DPH, DH and ZT at the 14-21cm depth were 84.3, 82, 178 and 97 kPa respectively. Amaranthus hybridus yield was highest on the DPH plots with an average weight of 10 stands weighing 108g.  Disc ploughed + harrowing was the best tillage practice considering the soil physical properties, penetration resistance and shear stress of the plots for the optimum yield of Amaranthus hybridus on the sandy loam field