Constructing an Arable Layer Through Chisel Tillage and Agropastoral Systems in Tropical Savanna Soils of the Llanos of Colombia uri icon

abstract

  • Integration of crop and livestock systems (agropastoralism) is a key strategy for intensifying agricultural production oil infertile acid savanna soils, and for reversing problems of soil degradation in the tropics. The main objective of this study was to evaluate the impact of strategies including vertical tillage ( 1, 2 or 3 passes of chisel), crop rotations (rice-soybean), and agropastoral systems (rice-grass alone pasture; rice-grass/legume pasture) on the build-up of ail arable layer and on grain yields of upland rice and soybean. We assessed the build-up of an arable layer in terms of improved soil physical characteristics (bulk density, penetration resistance), soil nutrient availability, soil phosphorus (P) pools, plant growth, and nutrient acquisition during the fourth year after the establishment of different treatments oil native savanna soil. The Soil used in this Study was an Oxisol in the eastern plains (Llanos orientoles) of Colombia. Agropastoral treatments (rice-grass alone pasture; rice-grass/legumes pasture) with vertical tillage decreased soil bulk density in the 0-20 cm soil layer by 12% when compared with the unmanaged native savanna. Consistent with bulk density, penetration resistance was also markedly decreased for 0-20 cm depth. Three passes of chisel (rice-soybean rotation) and pasture treatments (grass alone and grass/legUrne) improved the availability of Bray (II) P, K, Ca, and Mg in the 0-5 cm layer. The biologically available resin-P(i) and NaHCO(3)-P(i) each represented 5% of the total P and were significantly affected by chisel down to 10-20 cm depth. The moderately resistant NaOH-P represented, on average, 33% of total P in the 0-20 cm soil layer, and both NaOH-P(i) and NaOH-P(o) were significantly affected by chisel tillage. Results oil grain yields of upland rice showed that three passes of chisel Could have a negative effect on grain yield,. and that yields which declined over time declined more in agropastoral treatments than in rice-soybean rotation. These results indicate that the use of vertical tillage and agropastoral treatments can contribute to the build-LIP of an arable layer in low fertility savanna soils of the Llanos of Colombia as indicated by improved soil physical properties and nutrient availability. However, to take advantage of the constructed arable layer to improve crop yields, there is a need for developing better crop management strategies to control weeds. (C) 2003 by The Haworth Press, Inc. All rights reserved.

publication date

  • 2003
  • 2003