Enhanced Efficiency Fertilizers Research Articles

Durum Wheat Yield and N Uptake as Affected by N Source, Timing, and Rate in Two Mediterranean Environments

In nitrate vulnerable zones (NVZs), site-specific techniques are needed to match N availability with durum wheat (Triticum turgidum subsp. durum Desf.) requirements. Enhanced-efficiency fertilizers can improve efficient N supply and reduce leaching, contributing to sustainable agriculture. Two-year field experiments were carried out at two Mediterranean nitrate vulnerable zones in Central Italy (Pisa and Arezzo) to study the effects of nitrogen sources, timings, and application rates. The trial compared: (i) three N sources for the first topdressing application (urea, methylene urea, and urea with the nitrification inhibitor DMPP); (ii) two stages for the first topdressing N application (1st tiller visible—BBCH21 and 1st node detectable—BBCH31); (iii) two N rates: one based on the crop N requirements (Optimal—NO), the other based on action programme prescriptions of the two NVZs (Action Programme—NAP). Grain yield and yield components were determined, together with N uptake. The results showed that: (i) grain and biomass production were reduced with NAP at both locations; (ii) urea performed better than slow-release fertilizers; (iii) the best application time depended on the N source and location: in Pisa, enhanced-efficiency fertilizers achieved higher yields when applied earliest, while for urea the opposite was true; in Arezzo different N fertilizers showed similar performances between the two application timings. Different behaviors of topdressing fertilizers at the two localities could be related to the diverse patterns of temperatures and rainfall. Thus, optimal fertilization strategies would seem to vary according to environmental conditions.

Biodegradable Enhanced Efficiency Fertilizer Based on Biopolymers/Zeolites Films’ Assembly

Enhanced efficiency fertilizers (EEFs) have gained ground in the fertilizer trade. However, most of the EEFs marketed are not biodegradable. Therefore, it is necessary to produce EEFs that biodegra...

Meta-analysis of yield and nitrous oxide outcomes for nitrogen management in agriculture.

Improved nitrogen (N) use is key to future food security and environmental sustainability. While many regions still experience N shortages, agriculture is the leading global emitter of N2O due to losses exacerbated by N surpluses in other regions. In order to sustainably maintain or increase food production, farmers and their advisors need a comprehensive and actionable understanding of how nutrient management affects both yield and N2O emissions, particularly in tropical and subtropical agroecosystems. We performed a meta‐analysis to determine the effect of N management and other factors on N2O emissions, plant N uptake, and yield. Our analysis demonstrates that performance indicators—partial N balance and partial factor productivity—predicted N2O emissions as well as or better than N rate. While we observed consistent production and environmental benefits with enhanced‐efficiency fertilizers, we noted potential trade‐offs between yield and N2O emissions for fertilizer placement. Furthermore, we observed confounding effects due to management dynamics that co‐vary with nutrient application practices, thus challenging the interpretation of the effect of specific practices such as fertilization frequency. Therefore, rather than providing universally prescriptive management for N2O emission reduction, our evidence supports mitigation strategies based upon tailored nutrient management approaches that keep N balances within safe limits, so as to minimize N2O emissions while still achieving high crop yields. The limited evidence available suggests that these relationships hold for temperate, tropical, and subtropical regions, but given the potential for expansion of N use in crop production, further N2O data collection should be prioritized in under‐represented regions such as Sub‐Saharan Africa.

Nitrous oxide and methane emissions from soil and nitrogen uptake by eucalyptus fertilized with enhanced efficiency fertilizers

Evaluate which nitrogen fertilizer alone or in combination with additives for enhanced efficiency can reduce N2O and CH4 emissions of soil cultivated with eucalyptus and also increase nitrogen uptake. A pot experiment with eucalyptus seedlings was conducted with the application of urea or ammonium sulfate alone or in combination with polymer coatings, with nitrification inhibitor dicyandiamide (DCD), or with urease inhibitor N-(n-butyl)-thiophosphoric triamide (NBPT, only with urea). The sampling of gases and soil parameters was carried out over a 163-day period, and at the end of this period plant attributes were evaluated. When added to urea or ammonium sulfate, DCD reduced N2O emission by >95%, increased CH4 uptake by 11–20%, and increased the nitrogen uptake by eucalyptus by 27–30%. Meanwhile, polymer coated urea, polymer coated ammonium sulfate, or NBPT added to urea did not change these parameters. Ammonium sulfate alone reduced N2O emission by 38% and increased nitrogen uptake by 23% relative to urea alone. DCD mixed with urea or ammonium sulfate effectively reduced soil N2O emission and increased nitrogen uptake by eucalyptus plants; while polymer coatings or NBPT did not. Among the pure sources, ammonium sulfate was more efficient at reducing N2O emission and increasing nitrogen uptake compared with urea; but when DCD was added, N2O emissions were similarly low for both sources.

Controlled traffic farming delivers improved agronomic performance of wheat as a result of enhanced rainfall and fertiliser nitrogen use efficiency

ABSTRACT This study investigated the agronomic response and economic return of wheat grown in compacted and non-compacted soils to represent the conditions of non-controlled (non-CTF) and controlled traffic (CTF) systems, respectively. Yield-to-nitrogen responses were derived after application of urea, DMPP-treated urea, and UAN at rates between 0 and 300 kg ha−1 N. Soil properties were measured to guide parametrisation of APSIM, which was used to assess long-term (50 years) effects of CTF and non-CTF soil conditions on crop productivity, rainfall-use efficiency (RUE) and surface runoff. Grain yield and yield components were significantly higher in CTF compared with non-CTF. When N inputs were optimised, N use efficiency (NUE) was more than double in CTF (≈23%) compared with non-CTF (≈9%). RUE was about 15% higher in CTF, which concurrently reduced the amount of surface runoff compared with non-CTF. For years with average rainfall (240-mm in-crop), yield penalties of up 12% may be expected in non-CTF. APSIM simulations showed that increased productivity, and inter-annual yield stability, can increase gross margin of wheat by AUD30-50 ha−1 depending on in-crop rainfall and the tillage method used. In non-CTF systems, improvements in NUE and RUE are constrained by soil compaction. Enhanced efficiency fertilizers cannot compensate for other stresses caused by compaction and therefore cannot achieve the same NUE and RUE as the CTF system. Adoption of CTF in water-constrained environments improves profitability and resource-use efficiency.

Nitrogen Recovery from Enhanced Efficiency Fertilizers and Urea in Intensively Managed Black Walnut (Juglans nigra) Plantations

Intensively managed forest plantations often require fertilization to maintain site fertility and to improve growth and yield over successive rotations. We applied urea-based “enhanced-efficiency fertilizers” (EEF) containing 0.5 atom% 15N at a rate of 224 kg N ha−1 to soils under mid-rotation black walnut (Juglans nigra L.) plantations to track the fate of applied 15N within aboveground ecosystem components during the 12-month period after application. Treatments included Agrotain Ultra (urea coated with a urease inhibitor), Arborite EC (urea coated with water-soluble boron and phosphate), Agrium ESN (polymer-coated urea), uncoated urea, and an unfertilized control. Agrotain Ultra and Arborite EC increased N concentrations of competing vegetation within one month after fertilization, while neither Agrium ESN nor uncoated urea had any effect on competing vegetation N concentrations during the experiment. Agrotain Ultra and Arborite EC increased δ15N values in leaves of crop trees above those of controls at one and two months after fertilization, respectively. By contrast, Agrium ESN and uncoated urea had no effect on δ15N values in leaves of crop trees until three months after fertilization. Fertilizer N recovery (FNR) varied among ecosystem components, with competing vegetation acting as a sink for applied nutrients. There were no significant differences in FNR for all the urea-based EEF products compared to uncoated urea. Agrium ESN was the only EEF that exhibited controlled-release activity in this study, with other fertilizers behaving similarly to uncoated urea.

Modelling of N2O emissions from a maize crop after the application of enhanced-efficiency nitrogen fertilisers

ABSTRACT Emission of nitrous oxide (N2O) can be reduced using enhanced efficiency nitrogen fertilizers (EEFs), such as urease inhibitors and coating technologies. In this study, we evaluated the potential of EEFs to reduce N2O emissions in maize in a clayey Inceptisol subjected to no-till management under summer subtropical conditions, in southern Brazil. The EEF sources used included urea containing N-(n-butyl) thiophosphoric triamide (UR-NBPT), polymer-coated urea (UR-pol), in addition common urea (UR), nitrate (CN) and control treatment without the application of nitrogen fertilizer. N2O emissions were assessed using the static chamber method during one maize season and analyzed through non-linear regression, using a logistic model. The accumulated emission was 0.817, 0.613, 0.457 and 0.393 kg N2O ha−1, for CN, UR, UR-pol and UR-NBPT, respectively. The maximum daily emission of N2O did not vary between amidic forms, however for CN it occurred on the 4th day after application (DAA), while for urea forms it occurred on average at 5.3 DAA. The average N2O emission factor (FE-N2O) was 0.51%, approximately half the standard factor proposed by the Intergovernmental Panel on Climate Change (IPCC), which is 1%. The application of nitrogen increased the maize yield in relation to the control, but the sources of nitrogen did not differ, with an average yield of 10,455 kg ha−1. Based on our findings, the use of UR-NBPT and UR-pol in subtropical agroecosystems provides environmental benefits, by reducing N2O emissions in comparison with conventional nitrogen fertilizers (CN and UR), however, the EEFs did not offer agronomic advantages in maize yield.

Controlled traffic farming effects on productivity of grain sorghum, rainfall and fertiliser nitrogen use efficiency

Controlled traffic farming (CTF) is a mechanisation system in which all machinery has the same (or modular) working and track width so that field traffic can be confined to the least possible area of permanent traffic lanes. CTF enables productivity of non-compacted crop beds to be optimised for given energy, fertiliser and water (rainfall) inputs. This study investigated the agronomic response and economic return of grain sorghum grown in compacted and non-compacted soils to represent the conditions of non-CTF and CTF systems, respectively. Yield-to-nitrogen (N) responses were derived following application of urea, 3,4-dimethyl pyrazole phosphate-treated urea (DMPP), and urea ammonium nitrate (UAN, 32% N) at rates between 0 and 300 kg ha −1 N. Selected soil properties were measured to guide parametrisation of the Agricultural Production Systems Simulator (APSIM), which was used to assess long-term (55 years) effects of CTF and non-CTF soil conditions on crop productivity, rainfall use efficiency (RUE) and develop rainfall-runoff relationships. Grain yield and yield components (harvest Index, grain thousand-grain weight, number of grains) were significantly higher in CTF compared with non-CTF. On average, the most economic N rates, and corresponding grain yields, were 144 and 3428 kg ha −1 , and 100 and 1796 kg ha −1 for CTF and non-CTF, respectively. When N inputs were optimised, agronomic efficiency calculations showed 18% increase in CTF compared with non-CTF. Nitrogen use efficiency (NUE) was 1.75 times higher in CTF than in non-CTF. Rainfall-use efficiency was about 65% higher in CTF, which concurrently reduced the amount of runoff compared with non-CTF. Average rainfall season (330–450 mm in-crop) grain yield was 30% lower in non-CTF compared with CTF. For subtropical conditions of Australia, long-term APSIM simulations showed that increased productivity and inter-season yield stability can increase gross margin of grain sorghum by AUD74 ha −1 or greater depending on the adopted tillage system and in-crop rainfall. In non-CTF systems, improvements in NUE and RUE are constrained by soil compaction. Enhanced efficiency fertilisers, such as DMPP-treated urea, cannot compensate for other stresses caused by soil compaction and therefore cannot achieve the same NUE and RUE as the CTF system. Adoption of CTF delivers improved resource-use efficiency and profitability in rainfall-limited environments. Long-term (1960–2015) simulation of grain yield (A) and runoff (D) as a function of in-crop rainfall. Modelled data for grain sorghum-fallow cropping on a Red Ferrosol in Toowoomba (Queensland, Australia) in controlled (CTF) and non-controlled traffic farming (non-CTF) systems, respectively. Continuous lines show the best fit to predicted data. Dotted vertical lines show the 30th (left) and 70th (right) percentiles rainfall, respectively. • Controlled traffic farming (CTF) increased long-term grain yields by 30% in average-rainfall seasons. • Fertiliser nitrogen use efficiency (NUE) was 1.75 times higher in CTF compared with non-CTF. • Rainfall use efficiency (RUE) was 65% higher in CTF compared with non-CTF, which significantly reduced runoff. • Avoidance of (random) field traffic is a pre-requisite for jointly improving fertiliser NUE and RUE. • In non-CTF, improvements in NUE and RUE are constrained by compaction. • Enhanced efficiency fertilisers cannot compensate for other stresses caused by compaction.

Urea- Versus Ammonium Nitrate–Based Fertilizers for Green Sugarcane Cultivation

This study tested the hypothesis that enhanced-efficiency fertilizers, such as urea treated with NBPT, are a feasible substitute for ammonium nitrate–based fertilizers for green sugarcane cultivation. The experimental design included six N sources applied over sugarcane straw at two sites in Central-South Brazil. Treatments included ammonium nitrate, urea, and four urea-based fertilizers treated with different rates of the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) at two rates of N (50 and 100 kg ha−1), plus an additional control. Nitrogen status in the plant, the activity of glutamine synthetase (GS) and nitrate reductase (NR) in the leaves, and sugarcane stalk yield and quality were evaluated. At site 1, N rates increased the SPAD index, stalk yield, N uptake, and sugar yield. At site 2, N rates increased GS activity, N content, the SPAD index, and N uptake, but stalk and sugar yield were not increased due to large variability in these parameters. All N sources resulted in similar yields at both sites. These results were compared with those in the literature. Among 27 studies surveyed, the average sugarcane yield was 97.8 or 97.4 Mg ha−1 under ammonium nitrate or urea fertilization, respectively, and these averages did not differ by the Kruskal-Wallis test. The results of this study demonstrate that enhanced-efficiency fertilizers have the potential to reduce NH3 emissions from urea-based fertilizers in green sugarcane fields without affecting sugarcane yield.

Nitrous oxide emissions with enhanced efficiency and conventional urea fertilizers in winter wheat

Optimizing nitrogen fertilizer management can reduce nitrous oxide (N2O) emissions. This study tested if split applying enhanced efficiency fertilizers (EEFs) resulted in lower N2O emissions than applying equivalent rates of urea at planting. In semiarid southern Alberta, field trials were conducted during three years (planting to harvest) in rainfed winter wheat crops. Annual fertilizer rates ranged from 146 to 176 kg N ha−1. Fertilizer types were urea, and three EEFs (polymer-coated urea, urea with urease and nitrification inhibitors, and urea with a nitrification inhibitor). Each fertilizer type was applied three ways: 100% banded at planting, split applied 30% banded at planting and 70% broadcast in late fall, and split applied 30% banded at planting and 70% broadcast at Feekes growth stage 4 (GS4, post-tiller formation, wheat entering the greening up phase in the early spring). Nitrous oxide was measured using static chambers between sub-weekly and monthly from planting to harvest. Over three years, cumulative N2O emissions ranged from 0.16 to 1.32 kg N ha−1. This was equivalent to emissions factors between 0.009 and 0.688%. Cumulative N2O emissions and emissions factors did not differ between fertilizer types, but they were lower when fertilizer was split applied at GS4 compared to in late fall (P ≤ 0.10). Our study suggests that EEFs do not reduce N2O emissions from rainfed winter wheat crops, but a well-timed split application with a majority of fertilizer applied after winter can minimize N2O emissions.

The fertilizer release into water and soil as the biodegradation process in the sustainable material enhancing the fertilizer efficiency

Encouraging the development of sustainable agriculture is very important to reduce the negative effects of land overuse. Enhanced efficiency fertilizer combined with sustainable policies improves the effectiveness of fertilizer use. However, there is a gap in the literature to comprise how these materials behave concerning biodegradation, release in water, and soil, demanding more research. Composites of poly (3-hydroxybutyrate), sugarcane bagasse fibers, and potassium nitrate were melting-processed in an internal mixer chamber with different approaches to best trap the nutrient. For this purpose, we evaluated the composites regarding the nutrient release, in water and soil, and biodegradability. In water, the material with fibers released 20% less fertilizer than those without fibers during the first 9 h. The mathematical modeling performed to the release data indicated a predominance of the Peppas–Sahlin model among the three models studied. Also, fibers induced a decrease in nutrients lixiviation and favored biodegradation due to polymer crystallinity reduction. Sugarcane bagasse composites display the potential to slow the nutrients release and reduce the amount of polymer. • It is relevant the use of biopolymers and natural fibers for agricultural purposes. • The fibers decreased the lixiviation process in the soil. • The fibers decrease the matrix crystallinity favoring the biodegradation. • PA#2: Melt the polymer first incorporates better the nutrient and fibers. • The nutrient release occurs by diffusion and relaxation.

Biodegradation and viability of chitosan-based microencapsulated fertilizers

Enhanced efficiency fertilizers (EEF) are an important subject for sustainable materials. It is fundamental for the released nutrient and biodegradation in the soil to have synergy to ensure material harmlessness. Chitosan, montmorillonite, and KNO3 were considered to develop the EEF because of the high biodegradation potential of the final product. We correlated the material biodegradability and release in water and soil to their formulation. We assume the materials are biodegradable since the biodegradation efficiency achieved over 30 %. As the nutrient diffusion and matrix degradation happen concomitantly, we also observed that the clay delays degradation and the KNO3 improved it. Likewise, the storage period can change the biodegradability properties once the material started to degrade. Hereupon, the amount of nutrient delivered will match the amount consumed by the plant, the matrix will degrade and no residue will be left in the soil.

Widespread Use of the Nitrification Inhibitor Nitrapyrin: Assessing Benefits and Costs to Agriculture, Ecosystems, and Environmental Health.

Agricultural production and associated applications of nitrogen (N) fertilizers have increased dramatically in the last century, and current projections to 2050 show that demands will continue to increase as the human population grows. Applied in both organic and inorganic fertilizer forms, N is an essential nutrient in crop productivity. Increased fertilizer applications, however, create the potential for more N loss before plant uptake. One strategy for minimizing N loss is the use of enhanced efficiency fertilizers, fortified with a nitrification inhibitor, such as nitrapyrin. In soils and water, nitrapyrin inhibits the activity of ammonia monooxygenase, a microbial enzyme that catalyzes the first step of nitrification from ammonium to nitrite. Potential benefits of using nitrification inhibitors range from reduced nitrate leaching and nitrous oxide emissions to increased crop yield. The extent of these benefits, however, depends on environmental conditions and management practices. Thus, such benefits are not always realized. Additionally, nitrapyrin has been shown to transport off-field, and it is unknown what effects environmental nitrapyrin could have on nontarget organisms and the ecological nitrogen cycle. Here, we review the agronomic and environmental benefits and costs of nitrapyrin use and present a series of research questions and considerations to be addressed with future nitrification inhibitor research.

Spray-dried cellulose nanofibrils microparticles as a vehicle for enhanced efficiency fertilizers

This paper reports the role of cellulose and cellulose nanofibrils (CNFs) as a material to encapsulate nutrients applied in agriculture. Enhanced efficiency fertilizers have been a constant subject during the past decades to achieve slow and controlled release of the nutrients and decrease the environmental impacts caused by traditional fertilization. For this reason, it is important to use bio-based and biodegradable materials as a delivery method capable of covering the nutrients, retarding their solubility and availability in the environment, and avoiding the coating residue in the soil afterward. Here, we report the use of cellulose and cellulose nanofibrils to encapsulate nitrogen- and potassium-based nutrients. The nutrient was dissolved in a cellulose suspension and dried in a Mini Spray Dryer Buchi B-290. The materials obtained were classified as microspheres, microcapsules and tablets. They were characterized by morphology, physical and chemical structures, thermal properties, and release mechanisms. The nutrient availability in the environment was reduced through time for the microcapsules compared to the non-encapsulated and the microspheres. It displayed a reduction from 100 to 97.5% and then to 65.5% (from the non-encapsulated KNO3 to microsphere then to microcapsule, respectively) after 10 min of water contact. In addition, from 65.5 to 33% for tablet showing the superficial contact effect. The nutrient delivery depends on both the diffusional transport and the relaxational properties of the polymeric chain according to the kinetics mechanism. CNFs played an important role in the nutrient release behavior, which is of interest in the development of enhanced efficiency fertilizers.

Innovative management programme reduces environmental impacts in Chinese vegetable production.

China produces half of the world's vegetables. The production uses 1.7% of the global harvest area of crops but accounts for 7.8% of the chemical fertilizers and 6.6% of crop-sourced greenhouse gas (GHG) emissions worldwide. Using an innovative management programme, the integrated knowledge and products strategy (IKPS), we demonstrate opportunities for producing more vegetables with lower environmental impacts in China's vegetable production systems. Combining soil-crop system management practices with enhanced-efficiency fertilizer products, IKPS was tested through 54 site-year field experiments in China's major agro-ecological zones by a national research network over 12 years. Compared with current farming practices, the adoption of IKPS decreased the nitrogen (N) application rate by 38%, N surplus by 65% and GHG emissions by 28%, while increasing yield by 17%. Scenario analyses showed that adoption of IKPS in China's vegetable production could mitigate resource and environmental burdens while enhancing food and nutrition security.

Biochemical changes and distribution of nitrogen from bands of stabilised N-fertilizers in contrasting soils

‘Stabilised’ nitrogen (N) represents an important category of enhanced efficiency fertilizers (EEFs) in which chemicals added to urea granules inhibit target soil N transformation processes in order to optimize N availability for crop uptake. However the mechanistic understanding of how these inhibitors perform when urea-based fertilizers are banded, causing substantial modifications to the soil chemical environment, is poorly understood. In a 16-day laboratory incubation, the efficacies of the nitrification inhibitor (NI), 3,4-dimethylpyrazole phosphate (DMPP), and the urease inhibitor (UI), N-(n-butyl) thiophosphoric triamide (NBPT), were investigated in two soils by incubating two commercially available urea-based products containing these additives in bands at concentrations equivalent to 150 kg N ha−1 at row spacing of 1.8 m. When compared to a granular urea standard, DMPP did not provide any inhibitory benefits except when the inhibitor was able to diffuse beyond the zone affected by urea-N hydrolysis, within which considerable nitrification inhibition occurred because of the chemical conditions. The benefit of the NI was most significant in the soil with higher clay, organic matter and pH buffering capacity, with these properties confining the ureolytic-induced chemical changes and N transformations inhibitory zone closer to the fertilizer band. In contrast, the UI provided some benefit by slowing the rapid rise in pH, electrical conductivity and aqueous ammonia observed in standard urea bands, although the effects of NBPT were temporary (ca. 9 days) in both soils. The benefit of NI and UI technology relative to urea alone is likely to vary considerably between soils and fertilizer application methods. This study provides a physico-chemical approach to determining under what conditions the benefits of banded ‘stabilising’ EEF technology may be realised.

Three-dimensional dynamics of nitrogen from banded enhanced efficiency fertilizers

A range of enhanced efficiency fertilizers (EEFs) have been developed in response to widespread recognition of poor nitrogen (N) use efficiency (NUE) in agriculture; however, their effective utilization is not properly understood when applied in sub-surface bands. This study quantified soil chemical changes and the distribution of N species that arose from sub-surface banding of urea, a controlled release polymer-coated urea (PCU) and urea coated with either nitrification inhibitors (NIs) or a urease inhibitor (UI), over 71 days in a field trial. Banding NIs extended the duration of nitrification inhibition for up to 50 days longer than banded urea, although the duration of NI-conferred inhibition was dependant on the rate of NI-urea application. The UI preserved urea-N at a concentration which was 16-fold higher cf. standard urea over 7 days, but no urea-N was detected after 21 days. This suggests that the NUE benefits of UIs are transient when applied in sub-surface bands. Slow release of urea-N from banded PCU resulted in lower concentrations of N in the soil solution. This reduced N dispersal by ca. 50 mm cf. urea, resulting in a N-enriched zone which was considerably smaller. Relatively benign chemical conditions around PCU bands enabled rates of nitrification (NH4–N:NO3–N ratio of 46%) which were similar to urea. Collectively, these results demonstrate the relative efficacy and risks of the different EEF technologies, when applied in fertilizer bands. This knowledge supports the effective utilization of band-applied EEFs for improved NUE in agricultural systems.

Air quality, nitrogen use efficiency and food security in China are improved by cost-effective agricultural nitrogen management.

China's gains in food production over the past four decades have been associated with substantial agricultural nitrogen losses, which contribute to air and water pollution, greenhouse gas emissions and damage to human health. Here, we explore the potential to improve agricultural production practices that simultaneously increase yields while addressing these environmental challenges. We link agronomic research with air quality modelling for an integrated assessment of four improved nitrogen management strategies: improved farm management practices with nitrogen use reductions; machine deep placement of fertilizer; enhanced-efficiency fertilizer use; and improved manure management. We find that simultaneous implementation of the four strategies provides the largest benefits, which include: reductions in PM2.5 concentrations and associated premature deaths; increases in grain yields and grain nitrogen use efficiency; reductions in NO3- leaching and runoff and greenhouse gas emissions. Total benefits of US$30 billion per year exceed the US$18 billion per year in costs. Our findings indicate that policies that improve farmers' agricultural nitrogen management in China will improve both food security and public health while addressing multiple environmental challenges. Similar increases in attention on agricultural policy around the world are likely to provide large benefits in food security, environmental integrity and public health.

Spray-dried chitosan/nanocellulose microparticles: synergistic effects for the sustained release of NPK fertilizer

Enhanced efficiency fertilizers help to provide desirable nutrients to plants and release them in a prolonged time. The public concern about environmental protection and efficiency in the use of resources has increased the need to produce eco-friendly and high-performance products. In this work, we report the preparation and properties of the sustained release of spray-dried microparticles based on two biopolymers, chitosan, and nanocellulose. Cellulose rich solid was isolated from waste sugarcane bagasse by chlorine-free alkali peroxide procedure, yielding solids at 45.2%. Nanocellulose with sulfate groups attached on its surface was obtained by acid hydrolysis, and then it was incorporated into chitosan (CS) and NPK fertilizer solution, followed by spray drying to yield microparticles. The CS microparticles caused a decrease in the initial release rate of NPK, which resulted in extended-release of the entrapped nutrients (around 2 h). The incorporation of 10 wt.% nanocellulose to microparticles provided the most significant reduction on fertilizer release rate within 5 h. The work demonstrates the potential use of sulfated nanocellulose in biopolymeric matrices to design enhanced fertilizer release systems.

Global direct nitrous oxide emissions from the bioenergy crop sugarcane (Saccharum spp. inter-specific hybrids)

Sugarcane is the second largest bioenergy crop in the world and it accounts for 80% of global sugar production. Grown mostly in wet and warm tropics with relatively high nitrogen (N) fertiliser input and crop residue retention, sugarcane production is a significant source of nitrous oxide (N2O) emission. Yet, a global evaluation of research on N2O emission from sugarcane crop is lacking. Here, we conducted a meta-analysis using data from 141 measurements compiled from 15 sugarcane field studies reported from different countries to i) quantify N2O emissions and emission factors (EFs) globally, and for tropics and sub-tropics, and ii) identify the key factors that promote N2O emission. Our analysis shows that the global mean total N2O emission from sugarcane production reached 2.26 (CI: 1.93–2.62) kg N2O-N ha−1 yr−1 with an estimated EF of 1.21% (CI: 0.971–1.46%). N2O emissions increased exponentially with increase in N fertiliser rate, questioning the adequacy of Intergovernmental Panel on Climate Change (IPCC) default EF value (1%) for sugarcane N2O emission estimation. Mean total N2O emissions and EFs in tropics and sub-tropics did not vary significantly. Supplementing synthetic N fertiliser (SN) with organic amendments (OA) significantly increased mean N2O emission (~1.4-fold) and EF (~2.5-fold) compared to SN. A remarkable reduction in N2O emission (38.6%) and EF (61.5%) was evident when enhanced efficiency fertilisers (EEF) replaced SN. In contrast, crop residue removal had little impact on N2O emission and EF, but both parameters showed an upward trend with irrigation and increased rainfall. Soil carbon content and pH were emerged as key regulators of sugarcane N2O emission and EF. It is concluded that global sugarcane N2O emission could be significant and that there is considerable prospect for mitigating the emission through innovative nutrient formulations and precision agriculture that help meet crop nutrient demand without compromising environmental imperatives.