Tillage effect on nutrient uptake by wheat and cotton as influenced by fertilizer rate

Appropriate tillage and fertilizer management practices need to be developed for sustainable crop production without jeopardizing the quality of soil and the environment. Effects of tillage and fertilizer were studied for 4 years on wheat (Triticum aestivum L.) and for 2 years on cotton (Gossypium hirsutum L.) from 1995-1996 to 1998-1999. The experiments were conducted on a sandy clay loam (fine-loa-my, mixed, hyperthermic Typic Haplargids, USDA; Luvic Yermosol, FAO) in semi-arid region of Pakistan. Effects of three tillage methods as main plots and three fertilizer rates as sub-plots were studied in a split plot configuration. Tillage treatments were minimum till (MT), conventional till (CT), and deep till (DT). Three rates of NPK fertilizer (kg ha(-1)) were 60-20-25 (F-1), 120-40-50 (F-2), and 180-60-75 (F-3) for wheat; and 85-19-25 (F-1), 170-38-50 (F-2), and 255-57-75 (F-3) for cotton. Tillage treatments had significant effect on, grain yield of wheat in 2 out of 4 years. Considering average yield over all fertilizer treatments and four seasons, mean wheat yield was 3.4 Mg ha(-1) for MT, 5.0 Mg ha(-1) for CT and 3.6 Mg ha-1 for DT. Mean grain yield based on the average of all tillage treatments over four seasons was 3.2 Mg ha(-1) for F-1, 3.7 Mg ha(-1) for F-2, and 3.9 Mg ha(-1) for F-3. A similar trend was observed for wheat straw yields. Deep ploughing significantly increased seed cotton yield compared to MT and CT treatments. Averaged over all fertilizer treatments and two seasons, mean seed cotton yield was 2.3 Mg ha(-1) for MT, 2.4 Mg ha(-1) for CT and 2.5 Mg ha(-1) for DT. Similarly, the mean seed cotton yield was 2.1 Mg ha(-1) for F-1, 2.5 Mg ha(-1) for F-2 and 2.6 Mg ha(-1) for F-3. For both crops the interaction of tillage and fertilizer treatments was significant. Tillage systems did not significantly affect the plant tissue elemental contents of wheat (at tillering) and cotton (at flowering), However, the increasing rates of N, P and K caused a corresponding increase in tissue contents of N, P and K of wheat and cotton. Tillage and fertilizer treatments had a positive effect on nutrient uptake by wheat. CT and DT increased N, P and K uptake compared to MT treatment. (C) 2001 Published by Elsevier Science B.V.