GROWTH AND YIELD RESPONSE OF MAIZE (Zea mays L.) TO NITROGEN MANAGEMENT AND TILLAGE PRACTICES

Abstract

Most of the farmers of irrigated areas cultivate their fields with simple cultivator which creates a hard pan in the subsoil due to tilling the soil at same depth with same implement which has adverse effect on crop growth and yield. In addition to tillage nitrogen management is a key factor for better crop growth and yield. Two field experiments were conducted to evaluate the “impact of different tillage systems, nitrogen rates and time of application on growth, yield attributes, grain yield, quality and nitrogen uptake of hybrid maize” at the Agronomic Research Area, University of Agriculture, Faisalabad during 2008 and 2009. Both the experiments were laid out on a randomized complete block design (RCBD) with split plot arrangement using three replications, in a net plot size of 4.5m x 10m. In first experiment three tillage systems (conventional tillage, tillage with mouldboard plough + 2-cultivation and tillage with chisel plough + 2-cultivation) were kept in main plots and nitrogen levels (100, 150 and 200 kg N ha-1) in sub-plots. Different tillage systems significantly influenced soil physical properties, growth and yield characteristics as well as maize yield. Increasing tillage intensity resulted to improved soil porosity and reduced soil bulk density which led to higher crop yield. Chisel ploughed plots produced higher leaf area index (LAI), crop growth rate (CGR), leaf area duration (LAD), yield and yield components in comparison with other tillage systems. Maize yield with chisel tilled plots was 18% and 9% higher than mould board ploughed and conventionally tilled plots, respectively. Generally differences between different nitrogen application rates were more pronounced, increasing nitrogen application rate had positive impact on growth, yield components, yield and kernel quality. Increased LAI, CGR, grains weight per cob, 1000-grain weight and grain yield was recorded with 200 kg ha-1 nitrogen application. Maize yield with 200 kg ha-1 nitrogen application was 17% and 8.50% higher than 100 and 150 kg ha-1 nitrogen application respectively. The N uptake at 200 kg ha-1 nitrogen application was 240.88 kg ha-1 which was higher in comparison with other nitrogen treatments. Nitrogen application showed positive association with protein contents but negative association with grain oil and starch contents. In the second experiment different systems and nitrogen application timings were allotted to main plots and subplots respectively. Physiological, agronomic and qualitative traits in maize varied with nitrogen application timings. Physiological attributes like LAI and CGR was higher with nitrogen application in three splits i.e. 1/3 at sowing + 1/3 at knee height + 1/3 at tasseling, while the lowest was recorded with nitrogen application in two splits i.e. 1⁄2 at knee height + 1⁄2 at tasseling. The yield contributing parameters such as grains weight per cob and 1000-grain weight were found higher in plots fertilized with nitrogen in three splits. Similarly the highest grain yield was recorded in plots fertilized with nitrogen in three splits in comparison with other nitrogen treatments. The higher LAI, CGR and maize yield with nitrogen application in three splits was probably due to more availability of nitrogen at critical growth stages as compared to other nitrogen application timings. In addition to physiological and agronomic traits, nitrogen application at different growth stages also significantly affected the maize quality. Nitrogen application in three splits resulted to higher grain protein contents (8.23%) and (8.16%) during 2008 and 2009, respectively while the lowest grain protein contents recorded where all the nitrogen was applied at the sowing time. The higher protein contents in 2008 were probably due to drier environments at grain development as compared to 2009. Nitrogen uptake was also higher with nitrogen application in three splits while the lowest N uptake was recorded in sole application. Nitrogen uptake was higher during 2009, while lower during 2008 which might be attributed to nitrogen losses through leaching due to high rainfall at seedling stage during 2008. On the basis of economic analysis benefit-cost ratio (BCR) was calculated for both the experiments which showed that maize grown with nitrogen application @ 200 kg ha-1 in three splits by ploughing the soil with chisel plough was economical and gave more profit compared with other treatments. However, it is concluded that for obtaining higher maize yield and net income maize hybrid pioneer 31R88 should be grown with 200 kg ha-1 nitrogen application in three splits by preparing the field with chisel plough.