PERSISTENCE OF SUBSOIL COMPACTION EFFECTS ON SOIL PROPERTIES AND GROWTH OF WHEAT AND COTTON IN PAKISTAN

Abstract

The residual effects of subsoil compaction (below 0.15 m depth) on soil properties, growth, yields and nutrient uptake by irrigated wheat (Triticum aestivum) and cotton (Gossipium hirsutum) are reported. The study was initiated during 1997 on a sandy clay loam soil in a semiarid region of Pakistan. Results showed that the adverse effects of subsoil compaction on bulk density, penetration resistance, total porosity and air-filled porosity of soil persisted for at least four years. In the third and fourth years after the imposition of treatments, compaction decreased yields of wheat by 12–18% and by 7% for cotton. The corresponding reductions in nutrient uptake by wheat were 11–16% for N, 11–15% for P and 5–10% for K. For cotton, the values were 9% for N, 3% for P and 7% for K. Subsoil compaction decreased nutrient use efficiency by 16% in wheat and 5% in cotton. The reductions in water use efficiency were estimated to be 11% in wheat and 7% in cotton. Wheat root length density was also decreased in the subsoil.