Excessive Fertilizer Application Research Articles

Biochar alleviates the crop failure of rice production induced by low-nitrogen cultivation mode by regulating the soil microbes taxa composition.

To improve the nitrogen utilization efficiency and a series of environmental problems caused by excessive application of nitrogen fertilizer, actual agricultural production often reduced the usage ratio of nitrogen fertilizer. However, the reduction in nitrogen fertilizer not only affects the soil microenvironment but also leads to adverse effects on rice yield. Due to its unique properties, biochar can regulate soil nutrient distribution and significantly affect soil microbial community structure/functions. To further understand the effects of different levels of biochar on soil nutrient indicators, soil microorganisms and crop growth under the nitrogen-reduction condition, our experiment with four groups was set up as followed: 0%, 2.5% and 5% biochar application rates with 99kg/hm2 nitrogen fertilizer and one control group (the actual fertilizer standard used in the field:110kg/hm2) without no exogenous biochar supplement. The rice yield and soil nutrient indexes were observed, and the differences between groups were analyzed based on multiple comparisons. 16S ribosomal RNA and ITS sequencing were used to analyze the community structure of soil bacteria and fungi. Redundancy analysis was performed to obtain the correlation relationships between microbial community marker species, soil nutrient indexes, and rice yield. Path analysis was used to determine the mechanism by which soil nutrient indexes affect rice yield. The results showed that a higher application rate of biochar led to a significant increased trend in the soil pH, organic matter and total nitrogen content. In addition, a high concentration of biochar under nitrogen-reduction condition decreased the soil bacterial diversity but elevated the fungal diversity. Different concentrations of biochar resulted in these changes in the relative abundance of soil bacteria/fungi but did not alter the dominant species taxa. Taken together, appropriate usage for biochar under the nitrogen-reduction background could induce alteration in soil nutrient indicators, microbial communities and crop yields. These results provide a theoretical basis for exploring scientific, green and efficient fertilization strategies in the rice cultivation industry. Notably, the interaction relationship between rhizosphere microorganisms in rice and soil microbial taxa are not yet clear, so further research on its detailed effects on rice production is needed. In addition, the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis for the physiological functions of the soil microbes could only predict the potential metabolic pathways. Therefore, the next-generation metagenome techonology might be performed to explore detailed metabolic differences and accurate taxa alteration at the "species" level.

Integrated application of fertilization and reduced irrigation improved maize (Zea mays L.) yield, crop water productivity and nitrogen use efficiency in a semi-arid region

Water scarcity as well as soil degradation and environmental problems potentially caused by excessive application of chemical fertilizers are major challenges to agricultural production in semi-arid areas. It is crucial to explore a suitable and eco-friendly strategy to achieve sustainable production of maize with high crop water productivity and nitrogen use efficiency. Here, a two-year field experiment with three irrigation levels of W1 (220 mm), W2 (140 mm) and W3 (60 mm), and five fertilization types of no fertilizer (CK), chemical fertilizer (CF), bio-fertilizer combined with CF (CFB), organic fertilizer combined with 70% CF (CFO) and bio-fertilizer combined with CFO (CFOB) was conducted to investigate the effect on dry matter, N uptake and remobilization, grain yield, crop water productivity, nitrogen use efficiency and economic benefits of maize in 2021 and 2022. The results showed that the W2 and W3 decreased in the leaf area index, photosynthetic rate, dry matter accumulation, the maximum dry matter accumulation rate and actual crop evapotranspiration. Under W1 condition, the CFB improved the growth of maize, increased the dry matter and nitrogen accumulation and yield, with 8.1% and 7.4% higher than CF in 2021 and 2022, respectively. Under deficit irrigation (W2 and W3), CFOB significantly increased the leaf area index, photosynthetic rate, dry matter accumulation at later growth stage, in addition, CFOB increased the post-silking N uptake and the percentage in total N content, finally improved the grain yield with 23.8% and 22.8% under W2, 22.5% and 25.7% under W3 higher than that of the CF in 2021 and 2022, respectively. Irrigation and fertilizer showed a coupling effect on grain yield, crop water productivity, agronomy efficiency and nitrogen use efficiency. Overall, the CFOB under moderate deficit (W2) exhibited the highest water productivity, nitrogen use efficiency and economic benefits, as well as maintained the high yield, could be a promising approach to sustainable development of local maize.

Co-implementation of tillage and precision nutrient management practices on crop yield of kharif maize (Zea mays)

Our accustomed agricultural practices of tilling the soil continuously and excessive fertilizer applications caused not only a decrease in organic carbon content and soil degradation but also disturbed environmental harmony. With this backdrop, current study was carried out during rainy (kharif) seasons of 2018 and 2019 at the research farm of Trihut College of Agriculture, Dholi, Pusa, Bihar to evaluate the effect of different tillage and nutrient management practices on maize (Zea mays L.). The experiment was laid out in split-plot design with tillage as the main plot and nutrient management as the sub-plot. The results showed significantly superior maize grain yield in PB (6.1, 6.2 mg/ ha) and 60% RDN+GSGN (6.0, 5.9 mg/ha) over CT (4.9, 5.0 mg/ha) and RDF (5.1, 5.4 mg/ha) during 2018 and 2019. Similar trend was followed in stover yield, net returns and B:C ratio. Among path analysis, harvest index and no of grains/cob observed largest direct path coefficient of yield attributes to determine the maize grain yield and stover yield respectively. The results suggest that the adoption of conservation tillage and precise nutrient management practices will help in the realization of better yield with maximum profit by way of reducing the input capital apart from improving soil health thereby sustaining natural resources for future generations.

Overexpression of Cytosolic Glyceraldehyde-3-Phosphate Dehydrogenase 1 Gene Improves Nitrogen Absorption and Utilization in Potato

Nitrogen is one of the most important elements for improving potato yield. However, excessive application of nitrogenous fertilizer not only produces river and other environmental pollution but also increases agricultural production costs. In recent years, to explain the molecular mechanisms of nitrogen metabolites, some vital genes involved have been reported; however, only limited success has been achieved in potato. Here, we report that the expression of cytosolic glyceraldehyde-3-phosphate dehydrogenase 1 (StGAPC1) is increased under low-nitrogen stress. StGAPC1-overexpressing potato seedlings had more biomass and a significant increase in total nitrogen content and root nitrate influx rate compared to the wild type. The overexpression of StGAPC1 also increased the expression of nitrate transporters and increased ROS system activity to reduce hydrogen peroxide content under low-nitrogen stress. Our results provide a foundation for further research on StGAPC1 function in nitrogen absorption and utilization mechanisms in potato.

Leaching of soil legacy nitrogen in intact soil columns and significance of soil macropore structure

Excessive application of chemical fertilizers accumulates nitrogen in soil (soil legacy nitrogen), and its release has a long-term impact on environmental quality. The information regarding leaching of soil legacy nitrogen and role of soil pore structure is scarce. Fifteen undisturbed soil cores with a depth of ~200 mm were collected from five paddy fields in a subtropical area of China, and soil pore structure was characterized with X-ray computed tomography. The batch leaching column experiments were conducted to investigate the nitrogen leaching from the soil cores. In the leachate, inorganic nitrogen (NO3−–N and NH4+–N) accounted for 73–85 % of total dissolved nitrogen (TDN), which showed small variations among the five sampling sites. The NO3−–N, NH4+–N and TDN concentrations in the leachate over the number of leaching times could be well fitted with the Gaussian, exponential or linear models, suggesting that different nitrogen forms showed variable leaching dynamics. NO3−–N and TDN leaching losses continued to increase with the number of leaching times, whereas NH4+–N leaching from the soil had a threshold value. Combination of changes in soil nitrogen content after leaching, the lagging effect of soil legacy nitrogen may be partly attributed to the continuous transformation of NH4+–N and organic nitrogen into NO3−–N in the soils. Besides the nitrogen content in the soil, the most important factor of soil pore structure controlling NO3−–N and TDN leaching loss was the fractal dimension; NH4+–N was mainly controlled by connectivity. The present study highlighted the importance of soil pore structure and nitrogen format transformation in the leaching of soil legacy nitrogen.

Screening and promoting effect of grow-promoting fungi in rhizosphere of Angelica dahurica var. formosana

Excessive application of chemical fertilizer has caused many problems in Angelica dahurica var. formosana planting, such as yield decline and quality degradation. In order to promote the green cultivation mode of A. dahurica var. formosana and explore rhizosphere fungus resources, the rhizosphere fungi with nitrogen fixation, phosphorus solubilization, potassium solubilization, iron-producing carrier, and IAA-producing properties were isolated and screened in the rhizosphere of A. dahurica var. formosana from the genuine and non-genuine areas, respectively. The strains were identified comprehensively in light of the morphological characteristics and ITS rDNA sequences, and the growth-promoting effect of the screened strains was verified by pot experiment. The results showed that 37 strains of growth-promoting fungi were isolated and screened from the rhizosphere of A. dahurica var. formosana, mostly belonging to Fusarium. The cultured rhizosphere growth-promoting fungi of A. dahurica var. formosana were more abundant and diverse in the genuine producing areas than in the non-genuine producing areas. Among all strains, Aspergillus niger ZJ-17 had the strongest growth promotion potential. Under the condition of no fertilization outdoors, ZJ-17 inoculation significantly promoted the growth, yield, and accumulation of effective components of A. dahurica var. formosana planted in the soil of genuine and non-genuine producing areas, with yield increases of 73.59% and 37.84%, respectively. To a certain extent, it alleviated the restriction without additional fertilization on the growth of A. dahurica var. formosana. Therefore, A. niger ZJ-17 has great application prospects in increasing yield and quality of A. dahurica var. formosana and reducing fertilizer application and can be actually applied in promoting the growth of A. dahurica var. formosana and producing biofertilizer.

Incidence of Black Point on Wheat Seeds in Different Location of Uttarakhand, India

An experiment was conducted to determine the incidence of black point disease in wheat varieties with different locations caused by A. alternata fungal pathogens of wheat grain. Fresh seeds of popularly cultivated wheat varieties, preferably viz., GW 366, GW 496, Lok 1, and GW 1, were collected after harvesting season from the farmers’ fields of wheat growing areas of middle Uttarakhand viz., Sahaspur, Roorkee, Haridwar, and Dehradun. At least 50 samples were collected from each of the districts. Five primary samples were collected and mixed from the harvested seed lot to have composite samples. Working samples were prepared from composite samples by repeated halving method. The black point disease incidence might be due to the inherent boldness of the seeds. Florets remain more open in bold-seeded varieties, enhancing the chances of more seed infection during seed development. Moreover, low night temperatures during the flowering period, severe dew at the seed maturation stage, frequent and heavy crop irrigation, and excessive application of nitrogenous fertilizers may lead to a higher incidence of the black point disease. Besides, infected seeds reveal seed rot, necrosis, and shriveling. High humidity due to prolonged rainfall or heavy dew deposition during seed maturation favors the black point. As our research findings varied, GW366 is significantly the highest incidence of black point disease.

Combined Effects of Straw Return with Nitrogen Fertilizer on Leaf Ion Balance, Photosynthetic Capacity, and Rice Yield in Saline-Sodic Paddy Fields

Soil salinization is a prevalent global environmental issue that significantly hampers crop growth and yield. However, there has been limited research on the impact of nitrogen fertilization and various management practices in alleviating saline-sodic stress in crops. In order to examine the impact of combined straw and nitrogen fertilizer application on the physiological and photosynthetic characteristics of rice in saline-sodic paddy fields, a three-year field experiment was conducted in Jilin Province, China. The experiment was conducted as a split-zone trial, where the main zone consisted of straw (S) and the secondary zone consisted of nitrogen fertilizer (N). Two levels of straw were 0 t ha−1 (B) and 7 t ha−1 (T). Four nitrogen treatments were applied: 0, 150, 250, and 350 kg ha−1, denoted as N0, N1, N2, and N3, respectively. The results show that the combination of straw and nitrogen fertilizer has been found to effectively reduce the Na+/K+ value, malondialdehyde content, and the relative electric leakage of rice leaves in saline-sodic soil. Furthermore, it increases leaf water potential, relative water content, and chlorophyll content, thereby promoting rice photosynthesis and improving rice yield. The rice yield exhibited the greatest positive effect when straw and nitrogen fertilizer were combined at a rate of 250 kg ha−1. The effectiveness of this combination improves over time. However, it is important to avoid excessive application of nitrogen fertilizer when using straw returning. This approach not only ensures stable rice yield in saline-sodic fields, but also has positive effects on the economic impact of fertilizer application and soil environment preservation.

Remediation of the microecological environment of heavy metal-contaminated soil with fulvic acid, improves the quality and yield of apple

The excessive application of chemical fertilizers and pesticides in apple orchards is responsible for high levels of manganese and copper in soil, and this poses a serious threat to soil health. We conducted a three-year field experiment to study the remediation effect and mechanism of fulvic acid on soil with excess manganese and copper. The exogenous application of fulvic acid significantly reduced the content of manganese and copper in soil and plants; increased the content of calcium; promoted the growth of apple plants; improved the fruit quality and yield of apple; increased the content of chlorophyll; increased the activity of superoxide dismutase, peroxidase, and catalase; and reduced the content of malondialdehyde. The number of soil culturable microorganisms, soil enzyme activity, soil microbial community diversity, and relative abundance of functional bacteria were increased, and the detoxification of the glutathione metabolism function was enhanced. The results of this study provide new insights that will aid the remediation of soil with excess manganese and copper using fulvic acid.

Effects of different ratios of organic and inorganic fertilizer on rice yield and soil physicochemical properties under conventional and controlled irrigation conditions

AbstractWater and fertilizer management practices are critical in rice fields. Excessive application of fertilizer adversely affects soil physicochemical properties, consequently decreasing yield. A greenhouse experiment was conducted to determine the effect of high (L1), medium (L2) and low organic fertilizer ratios (L3) as well as chemical fertilizer alone (L4) and no fertilization (L5) under conventional (C) and controlled irrigation (M) on rice yield and soil characteristics. Statistically, the regression equation was developed by using principal component analysis to clarify the influence of different soil quality factors on rice yield. The results showed that controlled irrigation could increase soil temperature (ST), electrical conductivity (EC) and nitrogen content while decreasing soil pH. The application of organic fertilizer enhanced ST and decreased EC. Under equal nitrogen application conditions, rice yield increased with organic fertilizer application, and it was highest under L1, which was 2.7% higher than L4 and 22% higher than L5. In the case of irrigation methods, controlled irrigation application increased yield by 6% compared to conventional irrigation. The multiple linear regression equation showed that the cumulative contribution of variance of the two principal component eigenvalues reached 75%, among which soil pH, total nitrogen (TN) content and nitrate nitrogen (NO3−‐N) contributed positively to yield, while ammonium nitrogen (NH4+‐N), soil organic carbon (SOC), EC and ST showed negative effects on rice yield. Thus, our study findings can provide a scientific basis for improving management practices.

Characteristics of Nitrogen Output during Typical Rainfall in Different Sugarcane Growth Stages in a Southern Subtropical Watershed

Excessive fertilizer application, majorly nitrogen- and phosphorus-based fertilizers, in farmland has intensified environmental pollution of rivers, lakes, and other surface water bodies worldwide by agricultural non-point sources, especially the highly-mobile nitrogen. To solve nitrogen pollution in sugarcane areas, exploring the nitrogen output characteristics of agricultural watersheds in crop fields becomes necessary. Therefore, the objective of the study was to evaluate the characteristics of nitrogen output during typical rainfall events in different sugarcane growth stages in a southern tropical watershed in China. Dynamic monitoring of runoff and nitrogen concentration was carried out for four rainfall events and compared among four sugarcane growth stages (Establishment; Vegetative growth; Grand growth; Ripening) during the growing season of 2018 in the Nala watershed, Kelan Reservoir, Guangxi, China. The results showed that the total dissolved nitrogen flux of the 4 rainfall events ranged from 0.08 to 9.88 kg·hm−2 for the different growth stages. Nitrate nitrogen was the main component of the total flux, accounting between 75.7 and 92.1% of the total dissolved nitrogen while ammonium nitrogen accounted between 1.80 and 5.26% of the total flux for the 4 rainfall events. Total dissolved nitrogen and nitrate-nitrogen were significantly and negatively correlated with runoff (p < 0.05), while total dissolved nitrogen concentration did not correlate with runoff. The incipient scouring effect of total dissolved nitrogen and nitrate-nitrogen was not noticeable. The concentration of total dissolved nitrogen in the Nala watershed was inferior to class V water quality standard, indicating water eutrophication danger. The study showed that nitrogen nutrient inflow into the river was promoted by N-fertilization time and rainfall. Therefore, reasonably reducing N-fertilization dose and post-rain fertilization could effectively reduce nitrogen inflow into rivers and avoid the intensification of eutrophication in sugarcane areas. We recommend multiple years of studies to verify the possible impacts of differences in weather conditions.

Effect of Reducing Nitrogen Fertilization and Adding Organic Fertilizer on Net Photosynthetic Rate, Root Nodules and Yield in Peanut.

Long-term excessive application of chemical fertilizers can cause many problems, such as soil degradation and environmental pollution. Therefore, we reduced conventional nitrogen fertilization and added organic fertilizers in some cases to investigate the response of photosynthetic characteristics, root nodules and yield on reduced nitrogen fertilization. Compared to conventional nitrogen fertilization, the 25% and 35% nitrogen reduction treatments reduced the leaf area index, net photosynthetic rate, 100-fruit weight, 100-kernel weight and the yield of peanut, but had no significant effect on the kernel rate. With constant N fertilizer, adding organic fertilization alone increased leaf area index, chlorophyll, net photosynthetic rate and yield of peanut. In compounded treatments of nitrogen and organic fertilizer, the highest yields were achieved in the 25% N reduction with the 3000 kg/hm-2 organic fertilizer treatment (T3) and the 4500 kg/hm-2 organic fertilizer treatment (T4); furthermore, the net photosynthetic rate, leaf area index, yield and fertilizer contribution were significantly higher in these two treatments than in the conventional fertilizer treatments. Nitrogen fertilizer had significant effects on the quantity and fresh weight of root nodules. Concretely, nitrogen reduction increased the quantity and fresh weight of root nodules of peanut in the early stage of fertility but decreased them in the harvest stage. Nitrogen reduction with an additional organic fertilizer in the late stage of fertility increased the quantity and fresh weight of root nodules of peanut. Considering the property of root nodules was significantly positively correlated with net photosynthetic rate and yield, the arguments above may be the mechanism of the highest yields found in T3 and T4. This work can provide empirical and instructional support for a balanced fertilization strategy in peanut agriculture and high-yielding and efficient cultivation of peanut.

Optimizing Nitrogen Regime Improves Dry Matter and Nitrogen Accumulation during Grain Filling to Increase Rice Yield

Nitrogen (N) fertilizer is a critical element that affects rice yield. However, its effects on dry matter accumulation (DMA), N accumulation, and their physiological mechanisms with grain yield and N utilization efficiency still lack in-depth study. Three large-scale japonica rice varieties—Jinxiangyu 1, Nanjing 46, and Huaidao 5—were used in two field experiments with varying N fertilizer application rates to examine grain yield and N utilization efficiency. The results showed that: (1) In the range of 0~360 kg ha−1 total N application rate (TNAR), the rice yields of the three cultivars were maximum under the TNAR at 270 kg ha−1. The optimal TNAR for the highest yield of Jinxiangyu 1, Nanjing 46, and Huaidao 5 were calculated based on quadratic regressions with values of 305.5 kg ha−1, 307.6 kg ha−1, and 298.0 kg ha−1, and the corresponding yields were 10.3 t ha−1, 10.6 t ha−1 and 10.2 t ha−1, respectively. The N utilization efficiency decreased gradually with the increase in TNAR, and the recovery efficiency decreased from 35.7~38.19% to 29.61~31.59%. (2) The yield was significantly positively correlated with DMA and N accumulation from the heading stage (HD) to the maturity stage (MA). The DMA and N accumulation of HD-MA were significantly positively correlated with leaf photosynthetic rate, non-structural carbohydrate (NSC) accumulation in stems, root oxidation activity, zeatin (Z) + zeatin riboside (ZR) contents in roots, and nitrate reductase (NR) and glutamate synthase (GOGAT) activity in HD. (3) In the range of 0~216 kg ha−1 panicle N application rate (PNAR), the rice yield was maximum under the PNAR at 108 kg ha−1. The optimal PNAR for the highest yield of Jinxiangyu 1 was calculated based on the quadratic regression with values of 139.5 kg ha−1, and the highest yield was 9.72 t ha−1. The leaf photosynthetic rate, NSC accumulation in stems, root oxidation activity, Z + ZR contents in roots, and NR activity in leaves in rice were higher under 108 kg ha−1 PNAR. Excessive application of panicle fertilizer reduced the above physiological indicators and rice yield. The above results showed that optimizing N fertilizer could increase the leaf photosynthetic rate, NSC accumulation in stems, root oxidation activity, Z + ZR contents in roots, and NR activity from HD to MA, which was beneficial to improving DMA and N uptake during HD-MA, thus improving grain yield and N utilization efficiency in rice.

Genome-wide association study using specific-locus amplified fragment sequencing identifies new genes influencing nitrogen use efficiency in rice landraces.

Nitrogen is essential for crop production. It is a critical macronutrient for plant growth and development. However, excessive application of nitrogen fertilizer is not only a waste of resources but also pollutes the environment. An effective approach to solving this problem is to breed rice varieties with high nitrogen use efficiency (NUE). In this study, we performed a genome-wide association study (GWAS) on 419 rice landraces using 208,993 single nucleotide polymorphisms (SNPs). With the mixed linear model (MLM) in the Tassel software, we identified 834 SNPs associated with root surface area (RSA), root length (RL), root branch number (RBN), root number (RN), plant dry weight (PDW), plant height (PH), root volume (RL), plant fresh weight (PFW), root fractal dimension (RFD), number of root nodes (NRN), and average root diameter (ARD), with a significant level of p < 2.39×10-7. In addition, we found 49 SNPs that were correlated with RL, RBN, RN, PDW, PH, PFW, RFD, and NRN using genome-wide efficient mixed-model association (GEMMA), with a significant level of p < 1×10-6. Additionally, the final results for eight traits associated with 193 significant SNPs by using multi-locus random-SNP-effect mixed linear model (mrMLM) model and 272 significant SNPs associated with 11 traits by using IIIVmrMLM. Within the linkage intervals of significantly associated SNP, we identified eight known related genes to NUE in rice, namely, OsAMT2;3, OsGS1, OsNR2, OsNPF7.4, OsPTR9, OsNRT1.1B, OsNRT2.3, and OsNRT2.2. According to the linkage disequilibrium (LD) decay value of this population, there were 75 candidate genes within the 150-kb regions upstream and downstream of the most significantly associated SNP (Chr5_29804690, Chr5_29956584, and Chr10_17540654). These candidate genes included 22 transposon genes, 25 expressed genes, and 28 putative functional genes. The expression levels of these candidate genes were measured by real-time quantitative PCR (RT-qPCR), and the expression levels of LOC_Os05g51700 and LOC_Os05g51710 in C347 were significantly lower than that in C117; the expression levels of LOC_Os05g51740, LOC_Os05g51780, LOC_Os05g51960, LOC_Os05g51970, and LOC_Os10g33210 were significantly higher in C347 than C117. Among them, LOC_Os10g33210 encodes a peptide transporter, and LOC_Os05g51690 encodes a CCT domain protein and responds to NUE in rice. This study identified new loci related to NUE in rice, providing new genetic resources for the molecular breeding of rice landraces with high NUE.

Nitrate Migration and Transformation in Low Permeability Sediments: Laboratory Experiments and Modeling

The excessive application of fertilizers and the uncontrolled discharge of untreated wastewater on land contribute to the nitrogen pollution of groundwater. Low permeability sediment plays an important role in slowing down the migration of nitrate in groundwater systems. This study focuses on the mechanisms that affect nitrate transport in the low permeability layer. A soil column experiment was conducted and an MT3D transport model (a modular three-dimensional multispecies transport model) of nitrate was proposed. The results show that a low permeation layer could act as a strong barrier to nitrate migration and transportation, as demonstrated by the column soil experiment. The denitrification rates were controlled by many other factors, including nitrate concentration, flow rate, pH values and sediment particle characteristics. This indicated that denitrification is the most important factor in the attenuation of nitrate in low permeability sediments. This study clarified the law of migration and transformation of nitrate in low permeability soils and the factors that influence these processes. The results not only provide a basis for large-scale nitrate simulations, but also provide a reference for nitrate treatment in low permeability layers.

Combined Application of Arbuscular Mycorrhizal Fungi (AMF) and Nitrogen Fertilizer Alters the Physicochemical Soil Properties, Nitrogen Uptake, and Rice Yield in a Polybag Experiment

Excessive application of nitrogen fertilizer during rice cultivation leads to progressive soil contamination in the long term and increases production costs. An alternative to reduce over fertilization is to partially replace the fertilizer with microbes that promote nutrition and growth, such as arbuscular mycorrhizal fungi (AMF). We investigated the combination of four different rates of AMF (M): (M0: 0 g polybag−1, M1: 15 g polybag−1, M2: 30 g polybag−1, and M3: 45 g polybag−1) and three rates of nitrogen (N) fertilizer: (N0: 0 kg N ha−1, N1: 90 kg N ha−1, N2: 180 kg N ha−1) on Trisakti rice cultivar cultivated in polybag. Our findings indicate that the combination of 45 g AMF polybag−1 and 180 kg N ha−1 decreased soil bulk density by 38.02% and 37.24%, increased soil pH by 14.81% and 14.95%, soil porosity by 60.68% and 61.09%, soil organic matter by 28.62% and 30.46%, total N by 92.59% and 89.66%, available phosphorus by 30.12% and 29.85%, available potassium by 3.75% and 4.01%, rice plant height by 19.19% and 19.79%, tiller number by 25.27% and 26.08%, SPAD by 20.71% and 20.62%, flag leaf area by 107.76% and 108.02%, panicle length by 49.72% and 52.31%, panicle number by 67.44% and 72.35%, 1000-grain weight by 30.70% and 32.44%, root dry matter by 54.34% and 53.69%, shoot dry matter by 26.08% and 28.26%, root length by 54.68% and 56.44%, root volume by 42.73% and 43.37%, and N uptake by 107.93% and 108.06% compared to control during the early and late seasons, respectively. Conclusively, the combined application of AMF and N fertilizer increased the physiochemical properties, rice growth, rice productivity, and N uptake compared to AMF alone, N fertilizer alone, and the control treatment.

A holistic review on the assessment of groundwater quality using multivariate statistical techniques.

Water is an essential element in nature. It is used in drinking, irrigation, and industry mainly. Human health is directly linked to groundwater quality and is affected by poor groundwater quality caused by excessive fertilizer application and unhygienic circumstances. Because of increased pollution, investigating the water quality became a point of research for many researchers. There are numerous approaches to assessing water quality, and statistical methods are essential among them. This review paper discusses Multivariate Statistical Techniques, including Cluster Analysis, Principal Component Analysis, Factor Analysis, Geographical Information System, and Analysis of Variance, to name a few. We have presented the significance of each method concisely and how it is being used. In addition, an extensive table is prepared to demonstrate the individual technique along with the computational tool, the type of water bodies, and their respective regions. The advantages and disadvantages of the statistical techniques are also discussed therein. It is found that Principal Component Analysis and Factor Analysis are widely explored techniques.

Eco-Efficient Systems Based on Nanocarriers for the Controlled Release of Fertilizers and Pesticides: Toward Smart Agriculture.

The excessive application of pesticides and fertilizers has generated losses in biological diversity, environmental pollution, and harmful effects on human health. Under this context, nanotechnology constitutes an innovative tool to alleviate these problems. Notably, applying nanocarriers as controlled release systems (CRSs) for agrochemicals can overcome the limitations of conventional products. A CRS for agrochemicals is an eco-friendly strategy for the ecosystem and human health. Nanopesticides based on synthetic and natural polymers, nanoemulsions, lipid nanoparticles, and nanofibers reduce phytopathogens and plant diseases. Nanoproducts designed with an environmentally responsive, controlled release offer great potential to create formulations that respond to specific environmental stimuli. The formulation of nanofertilizers is focused on enhancing the action of nutrients and growth stimulators, which show an improved nutrient release with site-specific action using nanohydroxyapatite, nanoclays, chitosan nanoparticles, mesoporous silica nanoparticles, and amorphous calcium phosphate. However, despite the noticeable results for nanopesticides and nanofertilizers, research still needs to be improved. Here, we review the relevant antecedents in this topic and discuss limitations and future challenges.

Cultivation and Nitrogen Management Practices Effect on Soil Carbon Fractions, Greenhouse Gas Emissions, and Maize Production under Dry-Land Farming System

Effective nitrogen management practices by using two cultivation techniques can improve corn productivity and soil carbon components such as soil carbon storage, microbial biomass carbon (MBC), carbon management index (CMI), and water-soluble carbon (WSC). It is essential to ensure the long-term protection of dry-land agricultural systems. However, excessive application of nitrogen fertilizer reduces the efficiency of nitrogen use and also leads to increased greenhouse gas emissions from farming soil and several other ecological problems. Therefore, we conducted field trials under two planting methods during 2019–2020: P: plastic mulching ridges; F: traditional flat planting with nitrogen management practices, i.e., 0: no nitrogen fertilizer; FN: a common nitrogen fertilizer rate for farmers of 290 kg ha−1; ON: optimal nitrogen application rate of 230 kg ha−1; ON75%+DCD: 25% reduction in optimal nitrogen fertilizer rate + dicyandiamide; ON75%+NC: 25% reduction in optimal nitrogen rate + nano-carbon. The results showed that compared to other treatments, the PON75%+DCD treatment significantly increased soil water storage, water use efficiency (WUE), and nitrogen use efficiency (NUE) because total evapotranspiration (ET) and GHG were reduced. Under the PON75%+DCD or PON75%+NC, the soil carbon storage significantly (50% or 47%) increased. The PON75%+DCD treatment is more effective in improving MBC, CMI, and WSC, although it increases gaseous carbon emissions more than all other treatments. Compared with FFN, under the PON75%+DCD treatment, the overall CH4, N2O, and CO2 emissions are all reduced. Under the PON75%+DCD treatment, the area scale GWP (52.7%), yield scale GWP (90.3%), biomass yield (22.7%), WUE (42.6%), NUE (80.0%), and grain yield (32.1%) significantly increased compared with FFN, which might offset the negative ecological impacts connected with climate change. The PON75%+DCD treatment can have obvious benefits in terms of increasing yield and reducing emissions. It can be recommended to ensure future food security and optimal planting and nitrogen management practices in response to climate change.

Microbial community in buckwheat rhizosphere with different nitrogen application rates.

Microorganism plays a pivotal role in regulating sustainable development of agriculture. The excessive application of nitrogen fertilizer is considered to affect the microbial structure in many agricultural systems. The present study aimed to assess the impacts of nitrogen application rate on microbial diversity, community and functionality in rhizosphere of Tartary buckwheat in short-time. The nitrogen fertilizer was applied at rates of 90 kg (N90), 120 kg (N120) and 150 kg (N150) urea per hectare, respectively. The soil properties were measured chemical analysis and displayed no difference among treatments. Metagenome analysis results showed that the microbial diversity was not affected, but the microbial community and functionality were affected by the nitrogen application rate. According to the Linear discriminant analysis effect size (LEfSe) analysis, 15 taxa were significantly enriched in the N120 and N150 groups, no taxon was enriched in the N90 group. Kyoto Encyclopaedia of Genes and Genomes (KEGG) annotation results revealed that the genes related to butanoate and beta alanine metabolism were significantly enriched in the N90 group, the genes related to thiamine metabolism, lipopolysaccharide biosynthesis and biofilm formation were significantly enriched in the N120 group, and the genes related to neurodegenerative disease was significantly enriched in the N150 group. In conclusion, short-time nitrogen fertilizer application shifted the microbial community structure and functionality.