| dc.description.abstract | Investigations for the causes of immobility of tractors during land preparation and the
possibility of re-introducing the Double Cropping System (DCS) of rice production at the
Ahero Pilot Scheme CAPS) were carried out between December 1990 and May 1991.
The area of study is used for irrigation of rice and is mainly covered by heavy clay soils
with a clay content of more than 60 % .
The parameters that were monitored during the study were meteorological factors, soil
moisture content (SMC) and penetration resistance (PR) - as an indicator of the soil
bearing capacity measured. Meteorological parameters were monitored on daily basis
while SMC and PR were monitored on average once or twice a week. The study was
conducted in three blocks of the scheme that had shown persistent mobility problems over
a long period. In each block, the experiment was replicated four times. Sampling was
carried out at the drain, middle and feeder sides of each plot (replicate) and under ashes
or straw heaps. Sampling was also carried out in the field nurseries. At each location
the sampling depths were 0-5, 15,30,45 and 60 em. Simulation equations for predicting
SMC and PR were developed with the help of the data collected and the soil drying
model of Thornthwaite and Mather.
Through the simulation equations, it was found that with the given climatic conditions and
the rice varieties grown at APS, DCS of rice production is impossible as the soils do not
attain adequate strength by the time of land preparation. The major causes of mobility
problems were attributed to be the management of land preparation and of straw after
harvesting rice and lack of a hardpan. The effect of ashes or straw cover reduced PR by
about 3.6 times as compared with the no-cover situation. | en |
