Efficient rates of nitrogenous fertiliser for irrigated sweet sorghum cultivation during the post-rainy season in the semi-arid tropics

Abstract

Sorghum (Sorghum bicolor (L.) Moench) is a multipurpose crop with high tolerance to environmental stresses. To meet the increased demand for food and biofuel, current agricultural practices rely on the excessive use of inorganic nitrogen (N) fertiliser. However, excessive N fertiliser has resulted in negative environmental effects. In view of the varied N use efficiency (NUE) of plants under different environmental conditions, the aim of this study was to evaluate the efficient rates of N fertiliser in semi-arid tropics for sweet sorghum cultivation during post-rainy season by maximising NUE without compromising yield. Field experiments were conducted on two sweet sorghum cultivars with four different N fertilisation rates (0, 63, 90 and 150 kg N ha −1) during the post-rainy season in India. Grain and stalk yields increased with N fertiliser, but significantly only up to 90 kg N ha −1. The observed increases in grain yield were attributed by increases in kernel numbers. Corresponding with the differences in biomass, both relative growth rate (RGR) and crop growth rate (CGR) increased with N fertilisation rate up to 90 kg N ha −1. Component analyses of RGR and CGR revealed that both net assimilation rate (NAR) and leaf area index (LAI) significantly contributed with increasing rates of N fertiliser applications. Furthermore, studies of NUE indices showed that agronomic N use efficiency (ANUE, indicating yield production per unit of fertiliser N) responded comparably up to 90 kg N ha −1 , and decreased significantly thereafter. Analysis of ANUE components showed that the decline in ANUE at 150 kg N ha −1 was due to a decrease in physiological N use efficiency (PNUE), indicating that the absorbed N was not utilised efficiently for biomass and yield production, but merely accumulated. These results together suggest that 90 kg N ha −1 is an efficient N fertilisation rate suggested among the tested treatments for sustainable sweet sorghum cultivation during the post-rainy season in the semi-arid tropics.

Water and nitrogen input optimization for jujube trees under surge root irrigation based on weighted grey correlation model

“…This study showed that within a certain range of W&N, the crops yield and NI grow with the increase of W&N input, yet the yield and NI had a tendency to decrease when exceeding a certain threshold, so that only suitable W&N conditions could guarantee the highest yield and NI. The same conclusion has been drawn by other scholars [29][30][31][32] . Since the irrigation and fertilization has changed the soil's water and nutrient environment, there has been a positive correlation between root growth and soil moisture status within a certain range.…”

Nitrogen Availability and Physiological Response of Corn After 12 Years with Organic and Mineral Fertilization

“…1) and apparent N recovery efficiency (ANRE) (Eq. 2) were calculated according to Kurai et al (2015).…”

“…In this respect, it is expected that increased mineral N forms in the soil solution in phenological stages of higher root emission contributes to the increase in N uptake and shoot content. This promotes an increase in photosynthetic rate, because N is an essential component of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) and a key enzyme in carbon fixation (Kitajima et al 1997;Fyllas et al 2009), and results in higher N use efficiency (Kurai et al 2015). Nitrogen deficiency due to low availability in soil reduces chlorophyll content, compromises the photosynthetic process, and reduces dry matter and grain yield (Kirkby 2012).…”

Growth and Productivity of Brown Midrib Sorghum Mutant Line Patir 3.7 (Sorghum bicolor L. Moench) Treated with Different Levels of Nitrogen Fertilizer

“…Another study applying nitrogen fertilizers at the level of 90-120 kg N ha -1 showed an increase in the growth of sorghum production (Uchino et al, 2013). The response of sorghum to nitrogen fertilizer depends on genotype, climatic conditions, and the nature of the soil (Kurai et al, 2015). The novelty of this study is the use of new BMR sorghum mutant line material as a result of mutation technology produced in Indonesia.…”