Title of Thesis

Managing tillage, Organic and inorganic nitrogen in Wheat

Author(s)

Ahmad Khan

Abstract
Crop fertilization and reduced tillage practices simultaneously improve soil properties and crop yield. The objectives of the research were to evaluate urea (FN) and organic N under different tillage system in a 2-year field experiments for soil physiochemical properties, crop yield and N dynamics.The experiments were carried out at Agricultural Research Farm of NWFP Agricultural University Peshawar Pakistan. Tillage system included deep (DT), conventional (CT) and minimum (MT) tillage. The N treatments were 60, 120 kg FN ha-1, 10, 20 tons farmyard manure (FYM) ha-1 and 10 tons soybean residue (SR) ha-1. Farmyard manure and SR were applied solely and in combination with half of FN. A control treatment having no FN, FYM or SR was also included. The experimental design was RCB with split plot arrangement having three replications. Tillage were allotted to main plots, whereas N treatment to subplots. Minimum tillage had higher soil moisture, total N, mineral N and organic C as well as lower soil bulk density than DT. Higher straw, grain and total N uptakes as well as N uptake efficiency was observed in MT than DT. Deeply ploughed plots had higher N utilization efficiency, apparent N re-translocation and its efficiency, N harvest index and physiological efficiency of added N compared to MT. Minimum tillage enhanced emergence, booting, anthesis, milking, maturity and plant tallness compared to DT. Minimum ploughed plots had improved yield components, biological and grain yield. Similarly, MT imposed greater partition of dry matter to leaf, stem and maturity at different growth stages than DT. Emergence was higher in DT, whereas tillers m-2 and weeds m-2 in MT.Supplementing 20 tons FYM ha-1 with 60 kg FN ha-1 had increased soil moisture, mineral N and soil organic C but decreased soil bulk density. Soil C/N ratio was higher in plots receiving FYM solely. Urea N had increased soil pH, whereas soil total N was increased with 10 tons SR + 60 kg FN ha-1. Greater leaf N at boot, anthesis and maturity stages were measured in plots having 20 tons FYM + 30 kg FN ha-1, 10 tons FYM + 60 kg FN ha-1 and 120 kg FN ha-1, respectively compared to other treatments. Higher levels of FYM along with FN had increased stem N at earlier growth stage i.e. boot and anthesis compared to lower levels of FYM + 60 kg FN ha-1. Plots having 20 tons FYM + 60 kg FN ha-1 had greater stem N at boot and anthesis stage, but 10 tons FYM + 60 kg FN ha-1 application had higher stem N at maturity. Higher levels of FYM and FN jointly used had improved spike N at anthesis and maturity stage as well as straw, grain, total N uptakes and protein content compared to other treatments. Control and lower levels of N had greater nitrogen use, N utilization, apparent N re-translocation efficiencies and N harvest index than fertilized plots. In the same way, greater recovery and agronomic efficiencies of N were observed in 60 kg FN ha-1 plots compared to other fertilized plots.Uptake efficiency of N was higher in plots having 120 kg FN ha-1, whereas physiological efficiency of N was greater in plots having 10 tons SR + 30 kg FN ha-1. Fertilization had enhanced emergence and plant height, but control or 60 kg FN ha-1 enhanced vegetative and reproductive cycles. Spike m-2, grains per spike, thousand grains weight, biological and grain yield was higher in 20 tons FYM + 60 kg FN ha-1 compared to other treatments. Relative yield over control was higher in plots having FYM + FN used jointly. Increasing N had increased harvest index in all tillage practices, being higher in CT and in organic N +FN. Fertilization of 20 tons FYM with 60 kg FN ha-1 had increased average leaf area, leaf area index and specific leaf weight, but control had greater specific leaf weight. Leaf, stem and spike dry weight at boot, anthesis and maturity stages were higher in plots incorporated with 20 tons FYM + 60 kg FN ha-1. Incorporation of 10 tons FYM ha-1 had increased crop growth rate and net assimilation rate before anthesis. However, post anthesis crop growth rate and net assimilation rate were greater in plots having 20 tons FYM + 60 kg FN ha-1 and 10 tons FYM + 60 kg FN ha-1, respectively. Incorporation of FYM with N used jointly had greater emergence, tillers and weeds m-2 compared to other treatments. Value cost ratio (VCR) and relative increase in income (RII) were higher for FYM used as solely or combined with FN. Application of 20 tons FYM + 60 kg FN ha-1 had higher gross income ($505.2), net income ($455.0) over control, having VCR (9.1) and RII (75.8%) compared to other treatments. Integrated use of 20 tons FYM ha-1 with either 30 or 60 kg FN ha-1 under MT had improved crop productivity and soil fertility beside the monetary benefits and thus recommended for wheat sowing in agro-climatic condition of Peshawar, Pakistan.

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