Effect of Crop Cover on Temperature Regime of an Alfisol in the Tropics¹

Abstract

Effect of maize (Zea mays L.) and cowpea (Vigna unguiculata L. Walp) canopies on the thermal regime of an Alfisol was investigated in flat and ridged seedbeds. An interaction was observed between canopy characteristics and soil moisture availability that influenced the soil temperature. When the soil moisture was >0.08 cm3 cm−3 (suction <0.64 bar), plants were protected against temporary wilting in the second half of the day and the 5‐cm soil temperature decreased with an increase of maize and cowpea canopies. However, when the soil moisture was ≤0.0.8 cm3 cm−3 (observed on 53rd day after seeding of crops in 1980), the 5‐cm maximum soil temperature under maize and cowpea crops was higher by 3 and 0.2°C, respectively, than in an uncropped flat seedbed, and by 7 and 3.9°C, respectively, than in uncropped ridges. The 5‐cm soil temperature under maize was slightly lower in the early growth stages than under cowpea irrespective of the method of seedbed preparation. However, the reverse was true towards the crop's maturity. In addition to percent ground cover, soil moisture deficit, and the possible change in thermal conductivity were responsible for this reversal in soil temperature observed at the maturity stage. Soil temperature regime is strongly influenced by the interaction between canopy cover and soil moisture regime, on the one hand, and canopy height and density and wind velocity, on the other. The effect of increasing crop canopy on soil temperature on a given day (that provided an identical radiation for all plots) was studied for the flat seedbed by staggering the seeding dates of crops in the first season of 1981. On the 16th June (at approximately 50,40, and 20 days after seeding), and when the crops were not under moisture stress, an increase of maize canopy from 0 to 59.7% decreased the soil temperature range from 10.6 to 4.3°C at 1 cm and from 3.2 to 1.6°C at 20 cm depth. Similarly, an increase of cowpea cover from 0 to 100% decreased the temperature range from 10.6 to 1.7°C at 1 cm and from 3.2 to 0.6°C at 20 cm depth. Empirical models were developed that describe the effects of canopy cover, soil moisture, and radiation on maximum and mean soil temperatures at 1, 5, and 20 cm depths.

A Comparison of Four Processing Tomato Production Systems Differing in Cover Crop and Chemical Inputs

“…3). Other studies have found the same reduction in diurnal temperature fluctuations from mulches (Ghuman and Lal, 1983;Teasdale and Mohler, 1993). Soil temperature reductions were most dramatic for mulched plots during the periods when air temperatures were highest (data not shown).…”

Effect of topography on farm-scale spatial variation in extreme temperatures in the Southern Mallee of Victoria, Australia

“…The reduction in minimum temperature at the top of the areas with higher slope, while there was a crop in the farm, can be due to the flatter topography of the farm. The temperatures at the bottom of these areas were warmer than the top due to the crop cover and moisture as reported by Ghuman and Lal (1983) and Gonzalez-Dugo et al (2009). Overall, the extent of variation explained in maximum and minimum temperatures by the topography was low and the models produced more consistent and valuable results when the farm had a cover of wheat crop.…”

“…This indicates that there was much temperature variation because of the presence of the crop. Some of these crop effects may include the restriction of air movement, variation in soil moisture depletion by the crop, the extent of ground cover depending on the vigour of the crops and crop height (Ghuman and Lal 1983;Gonzalez-Dugo et al 2009). Further, due to these crop effects, patches of localised temperature were formed during the day, in contrast to the case when the farm was without a crop cover, on which the topography had some bearing.…”

Legume Cover Crops for Improving Crop and Soil Management in the Southern United States

“…The warm climate of the South also allows greater seasonal distribution of cover crop growth and offsets conditions for organic matter decomposition. Studies in Nigeria (21) suggest that both seasonal and daily fluc tuations in soil temperatures can be reduced by the use of cover crops in a no-tillage system. Also, as cover crop mulch tonnage increased, a reduction in soil temperature followed (39).…”