Effects of 42-year long-term fertilizer management on soil phosphorus availability, fractionation,adsorption–desorption isotherm and plant uptake in flooded tropical rice

Soil phosphorus(P) fractionation, adsorption, and desorption isotherm, and rice yield and P uptake were investigated in flooded tropical rice(Oryza sativa L.) following 42-year fertilizer and manure application. The treatments included low-input [unfertilized control without N, P, or K(C0N0)], farmyard manure(FYM)(C1N0), NP(C0NP), NPK(C0NPK), FYM + NP(C1NP), and high-input treatment, FYM + NPK(C1NPK). Grain yield was increased significantly by 74%over the control under the combined application of FYM + NPK. However, under low- and high-input treatments, yield as well as P uptake was maintained at constant levels for 35 years.During the same period, high yield levels and P uptake were maintained under the C0 NP, C0 NPK,and C1 NPK treatments. These are unique characteristics of a tropical flooded ecosystem, which is a self-sustaining system for rice production. The Fe–P fraction was highest compared to the Ca–P and Al–P fractions after 42 years of fertilizer application and was significantly higher under FYM + NPK treatment. The P adsorption capacity of soil was highest under the low-input treatment and lowest under long-term balanced fertilization(FYM + NPK). In contrast, P desorption capacity was highest under NPK and lowest in the control treatment. Long-term balanced fertilization in the form of FYM + NPK for 42 years lowered the bonding energy and adsorption capacity for P in soil but increased its desorption potential, increasing P availability to the plant and leading to higher P uptake and yield maintenance.

Carbon and water footprints of major crop production in India

Scarcity of water and emission of greenhouse gases(GHGs)are the two key environmental issues affecting crop production in India.Reducing the carbon footprint(CF)and water footprint(WF)of crop production can help to mitigate the environmental hazards that stem from GHG emissions and water scarcity.The CFs and WFs of three major cereal crops,rice,wheat,and maize,were estimated for the year 2014 under the environmental conditions in India,based on national statistics and other data sources.Total CFs(TCFs)of rice,wheat,and maize in India were estimated to be 2.44,1.27,and 0.80 t CO_(2)equivalent ha-1,respectively,and product WFs for rice,wheat,and maize in India were 3.52,1.59,and 2.06 m3 kg^(-1),respectively.Blue WF was found to be the highest in West India for rice and in South India for both wheat and maize,with the highest irrigation water use in these regions.There was a positive correlation between TCF and total WF,and hence mitigation of both was possibly simultaneous in various regions in India.Potential measures for mitigating GHG emissions and optimizing water use for rice,wheat,and maize production in India are recommended in this paper.

Rice straw recycling: A sustainable approach for ensuring environmental quality and economic security

One of the major challenges in Asian countries is the effective management of rice straw.To ensure food security for their ever-growing population,Asian countries grow more rice,leading to increasing rice straw generation.Burning of rice straw,a common practice,is detrimental to both environmental and human health.However,if managed effectively,rice straw has the potential to safeguard the sustainability of agricultural ecosystems and to uplift the economic security of the population depending on rice farming.Judicious management of rice straw involving minimum soil disturbance along with retention of residues alters the soil carbon cycle through reduced carbon emissions and increased levels of total soil organic carbon.Several alternative uses of rice straw,such as production of livestock feed,bioethanol,biochar,biogas,electricity,mushroom,and paper,can add prosperity to rice farmers’life by fetching extra income.It is evident that efficient management of rice straw is of enormous economic value.Therefore,it is essential to create awareness among the different rice stakeholders of these alternative economic avenues associated with rice straw.This review is an attempt to provide effective options for sustainable rice straw management and rice straw value chains for harnessing its economic potential.It further identifies gaps in our understanding of the effects of rice straw on ecological sustainability,particularly concerning the multifaceted connections between the diverse mechanisms of rice agro-ecosystems,which may greatly influence food security in the 21st century.