Changes of the pore space distribution of an Entic Haplustoll under different crops rotations in the Argentinian semi-arid region

Julio Iglesias G.1, Juan Galanlini S.2, Ramón Rosel! C.3, Ana Miglierina P.1 y Maria Landriscini R.3

The effect of crop and tillage systems and N-P fertilization on the distribution of the pore space of a sandy loam Entic Haplustoll of the Pampean semiarid region was studied.
The following tillage and crop sequence were evaluated: TT, continuous wheat; TP, one year wheat -one year Iivestock grazing rotation; TV, two years wheat- two years winter green crops (Vicia sativa with triticale).
TP received conventional tillage (short fallow, disk plowing and harrowing and flat seeding); TT and TV had conservation tillage (5 month fallow, chisel plowing and deep-furrow seeding). Half of all plots was annualy fertilized (f, 64 kg ha-1 of N and 37 kg ha-1 of P at seeding time) and the other half was not fertilized (nf).
Bulk density, soil water availability and pore space distribution were measured (small pores < 0.19 μm, medium 0.19-8.81 μm, and big > 8.81 μm). Results showed that changes in the pore space ocurred in the surface layers (0-0.07; 0.07-0.14 m). TT and TV systems showed higher proportion of medium pores and higer levels of water capacity than the TP treatments.

Keywords: soil tillage, crop rotation, pore space, water availability, Argentina.
1 Laboratorio de Humus (LAHBIS), Cepto. Agronomia, Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina.
2 Comisión de Investigaciones Científicas (CIC), Cepto. Agronomía (UNS), Bahía Blanca, Argentina.
3 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.