Groundnut (Arachis hypogea L) Growth and Yield as affected by Soil Compaction
1E. A. Aiyelari, 2S.O. Oshunsanya, 3J.A. Fagbenro, 4Favour O. Oritsejafor and 5Esther A. Ewetola
1,2&4Department of Agronomy,University of Ibadan, Ibadan, Nigeria.
3Department of Crop Production, Soil and Environmental Management, Bowen University,
P.M.B.284, Iwo, Nigeria.
5Department of Agronomy, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
1Corresponding author: soshunsanya@yahoo.com (Tel: +234-8130550047)
Accepted on July 9, 2013
Abstract
Soil compaction increases soil strength which can result in decreasing soil aeration, hydraulic conductivity, infiltration rate and crop yield. A green-house experiment was carried out at the University of Ibadan to examine the effect of soil compaction on root growth and yield of groundnut. Five kilograms of soil occupying a height of 12.9cm in the pot was compressed to heights of 12.7cm, 12.6cm, 12.4cm, 12.3cm, 11.8cm, and 11.5cm resulting in bulk densities of 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 and 1.7 Mg m-3 respectively. It was replicated five times. The sowing of two seeds of groundnut per pot was done before placing the loads on the soils. The results indicated that soil compaction had significant (P=0.001) effect on number of roots and root length with soil bulk density of 1.4Mg m-3 giving the best with respect to the two plant parameters. Total fresh biomass at harvest (12WAP) was higher in 1.4 Mgm-3 than in 1.7, 1.6, 1.5, 1.3, 1.2 and 1.1Mg m-3 bulk densities by 30.6, 28.6, 20.4, 22.5, 28.6 and 34.7% respectively. However, soil with bulk density of 1.3 Mgm-3 had significantly higher pod dry weight and seeds fresh weight than other treatments. The number of groundnut seeds per pot obtained from the soils with bulk densities of 1.7, 1.6, 1.5 and 1.3Mg m-3 were however not significantly different from one another but were significantly higher than groundnut seeds from soils with 1.2 and 1.1 Mg m-3 bulk densities. The force of harvesting groundnut increases with increase in soil compaction (R2 = 0.55) requiring more energy to uproot groundnut from compacted soil. Soil bulk densities of 1.5, 1.4 and 1.3 Mg m-3 gave the best results with respect to root density, root elongation, weight of pods and seeds. Therefore, compressing the type of soil used in this experiment beyond 1.3 Mg m-3 could have adverse effects on root growth and yield of groundnut. Farmers should be discouraged from using heavy implements to cultivate their farms.