Effect Of Tillage And Mulching Practices On Soil Properties And Growth And Yield Of Cowpea (<i>Vigna unguiculata</i> (L), Walp) In Southeastern Nigeria.

Abstract

This paper reports the field evaluation of the effect of tillage [tilled (MT) and untilled, (NT)], mulching material [Panicum maximum (p) and Chromolaena odorata (c)] and mulching method [incorporated (b), surface (s) and no mulch (o)] on soil properties and growth and yield of cowpea (Vigna unquiculata) in 2000 and 2001 cropping seasons, in Akwa Ibom State, Southeastern Nigeria. The study was a three-factor factorial in randomize complete block (RCB). The soil in 2000 and 2001 was strongly acidic. Organic C increased by about 83.6% at harvest in 2000 and declined by 16.4% in 2001. Available P declined by about 15.9% in 2000 and 59.6% in 2001. Base saturation increased by 9.6% in 2000 and decreased by 6.8% in 2001. Tillage and mulching practices improved water-stable aggregates >2mm by 16.6% in 2001. Bulk density was similar between MT and NT in 2000, but significantly lower (P<0.05) in MT (1.27g/cm3) than NT (1.35g/cm3) in 2001. Soil water content was similar in 2000 (mean = 7.74%) and 2001 (mean = 9.87%), but significantly lower in 2000 than 2001, whether MT or NT was used. Hydraulic conductivity (Ks) was almost similar among the tillage and mulching treatments, even as significantly higher values were obtained in tilled (mean = 10.37 cm/h) than untilled (mean = 7.87 cm/h) soil. Sorptivity and transmissivity were generally significantly lower in tilled than no-till soil, whether mulch was applied on the surface, incorporated or not. Equilibrium infiltration rate was significantly higher in no-till than tilled soil, and that Panicum maximum was significantly suited on tilled soil, while Chromolaena odorata was suited on no-till soil. It was also significantly higher in mulch-tilled soil than no-till soil. Cumulative infiltration was significantly higher in mulched no-till (mean = 77.7 cm) soil than mulched tilled (mean = 60.3 cm) soil, whether mulch was Panicum maximum or Chromolaena odorata. A similar trend was observed in the method of mulch application in no-till (mean = 78.3 cm) or tilled (mean = 70.4 cm) soil. Total root length was significantly greater in mulch-tilled plot ( mean = 175.3 cm) than in no-till plot (mean = 144.3 cm). Cowpea yield was significantly greater in tilled (mean = 130.2 g/m2) than no-till plot (mean = 16.0g/m2), and in mulched plots in 2001 (mean = 152.8g/m2) than in 2000 (mean = 77.0g/m2). The study demonstrates that residue mulch, incorporated in tilled soil or applied on the soil surface of tilled and no-till soil could improve soil properties and increase cowpea growth and yields.

Agro-Science Vol. 7 (2) 2008: pp. 118-128