Title of Thesis

Effect Of Zinc Fertilization In Integration With Organic And Mineral Nitrogen Sources On Maize Production Under Rainfed Conditions

Author(s)

Muhammad Sarwar

Abstract
In Pakistan, per hectare crop yields of rain-fed areas are relatively lower than obtained from irrigated areas. It is mainly due to less water availability and poor soil fertility. Lower soil organic matter limits micronutrients replenishment to soil solution.Therefore, this study was conducted to determine the zinc (Zn) requirement of maize, as well as to find out the interactive effect of organic and mineral fertilizer sources of nitrogen (N) on maize growth, yield and nutrient uptake. Experiments were conducted at National Agricultural Research Centre, (NARC) Islamabad, having latitude 33º 43΄ N, longitude 73º 04΄ E, and altitude 490 m. Soil of the study area is coarse loamy, mixed, hyperthermic Udic Ustochrept and belongs to Nabipur soil series. It is alkaline, calcareous, low in organic matter content, and deficient in N, P, K and Zn contents.
Initially, an incubation study was conducted to investigate the pattern of Zn retention, release and equilibrium of added Zn fertilizer in soil,. Four levels of zinc viz. 0, 2, 4 and 8 mg kg-1 were applied to soil weighing 300 g, and incubated by maintaining field capacity moisture at 30±1 °C for 15 days. Soil samples were drawn after 1, 5, 10 and 15 days for the determination of extractable Zn concentrations. Zinc availability / release were enhanced with increasing Zn rate, rendering the highest Zn concentration of 7.8 mg kg-1 in soil extract with 8 mg kg-1 Zn application. In the beginning, release rate was rapid and decreased gradually up to 15 days.
In the field experiment, main plots had four combinations of N sources viz. control; 100 % recommended dose of N from chemical fertilizer (CF); 75 % N from CF + 25 % N from farm yard manure (FYM), and 50 % N from CF + 50 % N from FYM. In the sub-plots, there were three levels of zinc fertilizer viz. 0, 4, 8 kg Zn ha-1. This experiment with the same treatments was conducted in both spring and summer seasons of 2008 on maize. Crop growth, yield parameters, photosynthesis rate, activity of nitrate reductase and superoxide dismutase enzymes, and nutrients uptake were measured. After the crop harvest, status of organic matter, N, P and Zn in soil was determined. Data on crop and soil parameters were subjected to statistical analysis of variance, and treatment means were compared by lsd test at P ≤ 0.05 to obtain statistical difference among them. Maize grain yield was at the highest with 75 + 25 % (CF + FYM) with 4 kg Zn ha-1, although it was statistically at par with that from 50 % + 50 % (CF + FYM) with 4 kg Zn ha-1 and 75 % + 25 % with 8 kg Zn ha–1. Zinc application showed a significant increase of grain and straw yield. Zinc uptake increased with the application of Zn fertilizer. Enzyme activities were enhanced with the application of Zn and FYM. The Study revealed that substitution of 25 or 50 % N with organic manure + 4 kg Zn ha-1 perform better than 100 % N fertilizer alone, with respect to improvement of crop growth, yield and soil fertility, and activities of superoxide dismutase and nitrate reductase. It reflects that integrated plant nutrient management ensures balanced supply of nutrients to the crop and improves stress tolerance as well.

1

2.1 Integrated Plant Nutrient Management
2.2 Interaction Of Zinc With Nitrogen Sources
2.3 Ipnm And Nutrient Uptake
2.4 Ipnm And Enzyme Activities
2.5 Zinc Dynamics In Soil
2.6 Ipnm Effects On Soil Characteristics

3.1 Site And Soil Characteristics
3.2 Soil Sampling
3.3 Procedures For Soil Analysis
3.4 Incubation Experiments
3.5 Field Experimentation
3.6 Crop Biometry
3.7 Procedures For Plant Analysis
3.8 Measurement Of Enzyme Activity
3.9 Economic Analysis
3.10 Meteorological Data
3.11 Statistical Analysis

4.1 Experiment 1: Dynamics Of Zn Applied In Soil
4.2 Experiment 2: Integration Of Nitrogen Source And Zinc