Effect of Discing and Weeding of Fallow on Soil Moisture Storage and Losses

The work was conducted on the heavy alkaline soils of Tozi which is situated in the Central Clay Plain of the Sudan. The top 91.5 cm of the soil was the active area of soil moisture changes. The net amount of soil moisture present during the rainy season or lost during the dry season decreased with increasing depth. In absence of weeds, disced and undisced condition of the surface soil during the rainy season did not affect the extent of moisture penetration. Also the presence of weeds till the end of August did not affect the extent of moisture penetration.

Where weeds grew up to the first week of October, the amount of water stored in the soil was less than where they did not. Growth of weeds till the end of August did not diminish the water storage efficiency of the soil. Fallow, kept free of weeds, stored in the rainy season 41 to 46 per cent of the rainfall received. Of this amount much was lost during the dry season. Loss of soil moisture during the dry season was a function of the weeds growing. The effect of discing on soil moisture conservation was merely through eradication of weeds.