La. Arevalo et al., THE EFFECT OF CATTLE GRAZING ON SOIL PHYSICAL AND CHEMICAL-PROPERTIESIN A SILVOPASTORAL SYSTEM IN THE PERUVIAN AMAZON, Agroforestry systems, 40(2), 1998, pp. 109-124
In a six-year-old peach palm (Bactris gasipaes) plantation, centrosema
(Centrosema macrocarpum), a leguminous forage plant, was established
as a cover crop which was eventually grazed. This experiment was desig
ned to monitor probable changes in soil physical and chemical properti
es and measure peach palm fruit production and live-weight gain of cat
tle grazing this silvopastoral system. The experiment was installed on
land that was previously cleared by a D7 bulldozer having a straight
blade that mixed the thin layer of topsoil with the acid subsoil (20-4
0 cm) and severely compacted the soil. The results demonstrated that t
he centrosema cover crop reduced soil bulk density, increased water in
filtration rates and reduced mechanical resistance. In general soil ph
ysical properties were improved with the use of Centrosema as forage a
nd cover crop. Soil acidity and aluminum saturation decreased consider
ably, while potassium concentrations increased. Calcium and magnesium
concentrations decreased over time as these minerals were stored in th
e pasture biomass, translocated to fresh peach palm fruits and/or expo
rted to animals. A strong competition for nutrients was observed betwe
en the peach palm plants and Centrosema. The low production of peach p
alm fruits was in response to mechanized land clearing during initial
establishment of the plantation, and also probably due to deficits of
N, P, K, Ca and Mg in the soil instead of being a consequence to the p
resence of cattle. The average increase in live-weight gains of the ca
ttle was at a rate of 445 g/animal/day during the four-years of the st
udy. Such an increase is substantially greater than those registered i
n the area under traditional grazing systems used in the region.