Saving environment through improving nutrient use efficiency under intensive use of agrochemicals in paddy fields

Nanocomposite-based smart fertilizers: A boon to agricultural and environmental sustainability

Fertilizers are indispensable agri-inputs to accomplish the growing food demand. The injudicious use of conventional fertilizer products has resulted in several environmental and human health complications. To mitigate these problems, nanocomposite-based fertilizers are viable alternative options. Nanocomposites, a novel class of materials having improved mechanical strength, barrier properties, and mechanical and thermal stability, are suitable candidates to develop eco-friendly slow/controlled release fertilizer formulations. In this review, the use of different nanocomposite materials developed for nutrient management in agriculture has been summarized with a major focus on their synthesis and characterization techniques, and application aspects in plant nutrition, along with addressing constraints and future opportunities of this domain. Further detailed studies on nanocomposite-based fertilizers are required to evaluate the cost-effective synthesis methods, in-depth field efficacy, environmental fate, stability, etc. before commercialization in the field of agriculture. The present review is expected to help the policy makers and all the stakeholders in the large-scale commercialization and application of nanocomposite-based smart fertilizer products with greater societal acceptance and environmental sustainability in near future.

Assessing agro-environmental sustainability of intensive agricultural systems

Sustainable production in water-scarce regions entails not to overshoot the sustainable blue water availability (BWA), which in turn requires addressing environmental flow requirements (EFRs). We explored the long-term effects of agricultural development, before (1984-1997) and during (1998-2018) the operation of the modern irrigation and drainage network of Tajan (TIDN), northern Iran, on the sustainability of blue water consumptions. A combination of different methods were applied to estimate hydrological EFRs of rivers, ab-bandans (traditional water reservoirs), and groundwater resources. Three major pollutants in the region's water resources, including nitrogen, phosphorus, and salinity, were used to estimate water quality EFR. Monthly agriculture water footprints (WFs) were calculated using the AquaCrop model, and then were compared with the region's BWA, which was calculated by subtracting monthly EFRs from monthly natural runoff. When WF exceeded BWA, the production system includes unsustainable water consumption. The EFR satisfaction of surface water decreased after TIDN operation by about 19%. Unmanaged nitrogen application and post-TIDN overexploitation of groundwater resulted in substantial increase in groundwater EFR violation. The TIDN led to more water consuming cropping pattern resulting in increased agricultural water consumption by about 73%. Overall, agricultural development in TIDN was beyond the capacity of the area, which resulted in up to about 167 MCM y^-1 unsustainable blue water consumption. Based on the results, the new framework presented for assessing agro-environmental sustainability could assist managers and policy makers to modify agricultural systems according to environment resilience.

Effect of Plant Buffer Zone–Antifouling Curtain Wall on Reducing Non-Point Source Pollution in Paddy Fields, China

In view of the nitrogen and phosphorus non-point source pollution caused by paddy field drainage in southern China, two paddy fields in Nanjing and Yuyao cities were selected to study the effect of plant buffer zone–antifouling curtain walls on reducing non-point source pollution. The results showed that the designed plant buffer zone–antifouling curtain wall systems could significantly reduce the concentration of total nitrogen (TN) and total phosphorus (TP) in drainage of the two paddy fields. Compared with paddy field drainage in Nanjing, the interception rate of TN in the plant buffer zone and antifouling curtain wall were 33.0% and 59.3%, respectively; the removal rates of TP were about 18.4% and 40.3%, respectively. In addition, the contents of ammoniacal nitrogen (NH3-N), nitrate nitrogen (NO3-N) and Chemical Oxygen Demand (COD) were also significantly reduced. For the Yuyao experimental area, compared to the paddy field without the soil plant buffer zone (the control), the concentration of each indicator in the discharge water of the paddy fields with the soil plant buffer system operation mode was significantly reduced, the rejection rate of the TP, TN, total dissolved phosphorus (TDP), NO3-N and NH3-N were 64.28%, 70.66%, 83.73%, 65.22% and 80.69%, respectively. In summary, the construction of a plant buffer zone–antifouling curtain wall (soil plant buffer zone) has an obvious effect on the reduction of non-point source pollution in paddy fields, which could improve yield and fertilizer utilization. The plant buffer zone–antifouling curtain wall could be popularized and applied in local areas and southern China.