Abstract
Nitrogen (N) losses are prevalent under South East Asia’s due to high N fertilizer inputs, but low N fertilizer use efficiency. This leaves a large quantity of reactive N at risk of loss to the environment. Biochar has been found to reduce N losses across a variety of soil types, however, there is limited data available for semi-arid climates, particularly at a field-scale. Herein we present an exploration of the biological and chemical enhancement effects observed of a cotton stalk-based biochar on wheat growth and yield under arid field conditions. The biochar was treated with urea-N and biofertilizer (bio-power) in different treatment setups. The six experimental treatments included; (i) a full N dose “recommended for wheat crops in the region” (104 kg N ha−1) as a positive control; (ii) a half N dose (52 kg N ha−1); (iii) a half N dose + biofertilizer (4.94 kg ha−1) as a soil mixture; (iv) a half N dose + biofertilizer as a seed inoculation; (v) a full N dose as broadcast + biochar (5 t ha−1) inoculated with biofertilizer; and (vi) a full N dose loaded on biochar + biofertilizer applied as a soil mixture. The half dose N application or biofertilizer addition as soil mix/seed inoculated/biochar inoculation with biofertilizer caused reduced wheat growth and yield compared to the control (conventional N fertilization). However, co-application of chemically enhanced biochar (loaded with a full N dose) and biofertilizer as soil mixture significantly increased the crop growth rate (CGR) and leaf area index (LAI). A significantly higher crop growth and canopy development led to a higher light interception and radiation use efficiency (RUE) for total dry matter (TDM) and grain yield (11% greater than control) production compared to the control. A greater grain yield, observed for the full N dose loaded on biochar + biofertilizer applied as a soil mixture, is attributed to prolonged N availability as indicated by greater plant and soil N content at harvest and different crop growth stages, respectively. The present study has improved our understanding of how the application of nitrogen loaded biochar and biofertilizer as soil mixtures can synergize to positively affect wheat growth and soil-nitrogen retention under arid environmental conditions.
Highlights
The increasing food demands of an ever-increasing population have been identified as key indicators of crop intensification and the non-judicious use of synthetic chemicals [1].For instance, rather than using fertilizers containing a balanced mix of major soil nutrients, it is not uncommon for high levels of fertilizers containing only nitrogen (N) to be applied to land as they are often cheaper
Treatment vi (104 kg N ha−1 loaded on biochar + biofertilizer used as soil mixture) produced the highest leaf area index (LAI) (1.86, 4.63, 2.92) at different time-periods (64, 90 and 124 days after sowing (DAS), respectively)
The results revealed a positive relationship with a high-value determination coefficient (R 2 = 0.94) between total intercepted photosynthetically active radiation (TIPAR) and total dry matter (TDM) and crop growth rate (CGR), which showed a dependency of biomass production and growth rate for light interception through the wheat crop canopy (Figures 3 and 4)
Summary
Rather than using fertilizers containing a balanced mix of major soil nutrients, it is not uncommon for high levels of fertilizers containing only nitrogen (N) to be applied to land as they are often cheaper. This has resulted in detrimental effects on the environment, such as nitrogen leaching to groundwater [2], and increased greenhouse gas emissions. The wheat crop yield depends on efficient nitrogen (N) use to achieve higher yields [20]. It is essential for the nitrogen supply to be replenished in order to maintain or increase crop yield [21]
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