EFFECTS OF COVER MANAGEMEMT PRACTICES ON PHYSICAL PROPERTIES RUNOFF AND EROSION IN NSUKKA AANDY LOAM SOIL

ABSTRACT
A two -year (2004/2005) field investigation was carried out on the runoff plots at the University
of Nigeria Nsukka farm, to monitor the effects of cover management practices on physical
properties, runoff and soil loss in Nkpologu sandy loam soil. The management practices were
barefallow (BF), cocoyam (CY) sorghum (SG), legume (CP) and grass (PM), under no-till
practice. There was no change in soil texture due to treatments. The treatments generally
increased soil organic matter content compared with the control. Bulk density was significantly
increased in all treatments with highest value (1.65Mg/m3) in barefallow and lowest value (1.49
Mg/m3) in grass. There was no significant decrease in porosity and pore size distribution. Mean
weight diameter (MWD) of aggregates and saturated hydraulic conductivity (Ksat) were
significantly increased (p = 0.05).

The least values for MWD (1.06mm) and for Ksat
(25.80cm/hr) and highest for MWD (2.09mm) and for Ksat (49.20cm/hr) were obtained under
barefallow and grass treatments respectively. The percentage aggregate size above 2.0mm was
highest in grass and lowest in barefallow. Calculations showed significant positive correlation (r
= 0.50 at P = 0.05) between organic matter and MWD. There was significant negative correlation
(r = -0.60 at P = 0.05) between organic matter and bulk density and significant positive
correlation (r = 0.80 at P = 0.05) between organic matter and saturated hydraulic conductivity.
The pentades were generally wet during the study periods in the two seasons. Cumulative runoff
was highest in barefallow and lowest in sorghum (87mm and 41mm respectively). The highest
soil loss of 1.13kg/m2 and relatively low loss of 0.55kg/m2 were obtained in cocoyam and
sorghum respectively in 2005.

Runoff and soil loss were reduced by 100% under grass and
legume. Cocoyam and sorghum reduced runoff by 20% and 53% respectively. Sorghum reduced
soil loss by 35%, while there were no differences in the percentage reductions due to barefallow
and cocoyam treatments. Runoff as percentage of rainfall was highest in barefallow and lowest
in sorghum (60.6% and 19.9% respectively). Erosion rate was lowest in sorghum
(0.2kg/m2/month) and highest (0.4kg/m2 month) in cocoyam. Under BF the rate was
0.3kg/m2/month. The mean yield of cocoyam was 1.35t/ha and that of sorghum was 0.88t/ha