| dc.description.abstract | In many agricultural systems in the semi-arid tropics, crops use only a small fraction of the total rainfall. Agroforestry can greatly
reduce some losses, especially on hi II slopes, where soi I evaporation, runoff and soi I losses are important. This paper repoi [S on soi I
evaporation from a rotation of intercropped maize and cowpea between contour hedgerows of pruned Senna siamea trees as well as
trimmed Panicuni maximum grass strips on a 14% hill slope at a semi-arid site in Machakos, Kenya. There were five treatments in
order to separate effects of Senna mulch, hedges, and grass strip'. Micro-lysimeters were placed between crop rows for three
seasons. It followed from their results that, for the three seasons concerned, tree prunings as mulch reduced soil evaporation as
percentage of rainfall in the measuring period by absolute values of9%, 4% and 6% compared to the contr sole maize and cowpea
with bare soil. The influence of the hedge added to this only insignificantly, even at I m distance. The non-mulched plots had soil
evaporation reduced by only between on average I% and 4% in absolute values comparedro the control over all the seasons, with a
maximum of 5% close to the hedge in the first season. Mulch apparently is the main evaporation reducing factor. Soil evaporation
reached the highest percentage of rainfall in the long rains of 1994, becoming 65% in sole maize. It was 50% for sole cowpea in the
1994/1995 short rains and for sole maize in the next long rains. The highest value, although an upper limit could largely be
understood from highest early season evaporative demands, rainfall distributions and low crop cover. The other values were in line
with earlier reports for dry areas. Some advantages and disadvantages of these agroforestry systems are reviewed. | en |
