TITLE:
Effects of Nitrogen Rates on Cotton under Different Plant Available Water Capacity Sites in Pyawbwe, Central Dry Zone of Myanmar
AUTHORS:
Thu Zar Win, Aye Aye Than, Kyaw Ngwe, Aye Aye Khaing
KEYWORDS:
Cotton, Yield, Plant Available Water Capacities, Water Use Efficiency, Nitrogen, Nitrogen Use Efficiency
JOURNAL NAME:
Open Access Library Journal,
Vol.8 No.2,
February
26,
2021
ABSTRACT: Soil water content and nutrient availability are two main factors of limiting plant growth and productivity in an uncertain rainfall area likes central dry zone of Myanmar (CDZ). The aim of this research was to observe the effects of nitrogen (N) rates on rainfed cotton (Gossypium hirsutum L.) under different plant available water capacity (PAWC) sites. The field experiments were conducted during post-monsoon season 2019 at two sites, Pawaingyoe and Kokkokhahla, of Pyawbwe Township having different PAWC. In both sites, six levels of N rate (T1 = 0, T2 = 60, T3 = 90, T4 = 120, T5 = 150 and T6 = 180 kg N ha-1) were laid out in randomized complete block design with four replications and cotton variety Ngwechi-6 was tested. The effects of N rates on growth, yield, residual soil NO3--N, nitrogen use efficiency (NUE), water use efficiency (WUE) and benefit cost ratio (BCR) were examined. Results showed that PAWC, soil N and OM levels of the clay loam soil from Pawaingyoe was higher than those of the sandy loam soil from Kokkokhahla. In Pawaingyoe, maximum seed cotton yield (2364 kg ha-1), NUE, WUE, BCR and lower residual soil NO3--N were achieved by T2 (60 kg N ha-1). In Kokkokhahla, maximum seed cotton yield (1976 kg ha-1), WUE, BCR and higher residual soil NO3--N were found in T4 (120 kg N ha-1), however, which were followed by T3 (90 kg N ha-1) with the statistically similar seed cotton yield (1787 kg ha-1), the maximum NUE and lower residual soil NO3--N. Therefore, it may be assumed that T2 (60 kg N ha-1) was the most suitable rate for Pawaingyoe site while within the range between T3 and T4 (90 to 120 kg N ha-1) was appropriate for Kokkokhahla. The finding of this study could be contributed some suggestions to the recommendation for cotton N rates under similar circumstances.