Excessive Fertilizer Application Research Articles

Characteristics and Driving Mechanisms of Shallow Groundwater Chemistry in Xining City

Groundwater is one of the major sources of water supply, especially in the western arid regions. However, with the deepening of the western development strategy, industrialization and urbanization have increased groundwater resource demands in Xining City. Overexploitation and utilization have led to a series of changes in the groundwater environment. Identifying the chemical evolution characteristics and formation mechanism of groundwater is crucial for preventing its deterioration and ensuring sustainable use. By combining hydrochemistry and multivariate statistical techniques, the chemical characteristics of groundwater in Xining City were analyzed, and the formation mechanism of groundwater and the influence of different factors were discussed. The results showed that there were as many as 36 chemical types of shallow groundwater in Xining City, mainly HCO3-Ca(Mg) (60.00%) and HCO3·SO4-Ca(Mg) (11.81%). There were 5-6 types of groundwater chemical types in bare land, grassland, and woodland. Groundwater chemical types in construction land and cultivated land were more complex, up to 21 types, indicating that they were strongly affected by human activities. The chemical evolution process of groundwater in the study area was mainly affected by rock weathering and leaching, evaporative crystallization, and cation exchange. The main controlling factors were water-rock interaction (contribution rate 27.56%) and industrial wastewater discharge (contribution rate 16.16%), acid-base environment (contribution rate 16.00%), excessive application of chemical fertilizers and pesticides (contribution rate 13.11%), and domestic sewage (contribution rate 8.82%). On account of the chemical characteristics of groundwater in Xining City and the influence of human activities, the management and control suggestions on the development and utilization of groundwater resources were put forward.

Effect of Chicken Manure Fermentation Extract as an Alternative to Chemical Fertilizer on Cucumber Growth and Soil Microbiome Environment

ABSTRACT In recent years, the destruction of the soil environment caused by excessive application of chemical fertilizers has attracted attention to using organic fertilizers to replace chemical fertilizers. Previous studies have shown that chicken manure fermentation extract (CMFE) as an organic fertilizer may also directly influence soil nutrient availability from the soil native pool and fertilizer application. However, it is unclear whether application CMFE can partially replacing chemical fertilizer to reduce the amount of chemical fertilizer without reducing cucumber yield. Therefore, an experiment was conducted in Yantai Agricultural Science Academy of Shandong Province in 2018 and 2019. In 2018, five fertilization combinations were set up, namely CK (900 kg·ha−1 chemical fertilizer), T1 (750 kg·ha−1 chemical fertilizer +150 L·ha−1 CMFE), T2 (675 kg·ha−1 chemical fertilizer +225 L·ha−1 CMFE), T3 (600 kg·ha−1 chemical fertilizer +300 L·ha−1 CMFE) and T4 (525 kg·ha−1 chemical fertilizer +375 L·ha−1 CMFE). Selected the optimal combination T3 for testing in 2019. The yield, quality, photosynthesis and growth indicators of cucumber, as well as soil nutrients and microbial content were determined. The results showed that the fertilization combination of 600 kg·ha−1 chemical fertilizer +300 L·ha−1 CMFE (T3) can minimize the amount of chemical fertilizer used without reducing yield. Compared with conventional fertilizer application, CMFE partially replacing chemical fertilizer did not reduce cucumber yield, but significantly increased cucumber vitamin C and protein content. CMFE partially replacing chemical fertilizer increased the root to shoot ratio as well as the fresh and dry weight of vegetative organs in cucumber, optimizing the growth and development of cucumber. Compared with conventional fertilizer application, CMFE partially replacing chemical fertilizer increased the content of soil organic matter, improved the composition structure of soil microbial community, increased the relative abundance of Actinomycete and Acinetobacter, and reduced the relative abundance of Bacteroides, Ascomycota, and Basidiomycetes. Overall, CMFE partially replacing chemical fertilizer optimized the growth and development of cucumbers, increased the root to shoot ratio, increased soil organic matter content, increased microbial abundance and diversity, and improved the composition structure of soil microbial communities. Therefore, in order to reduce the use of fertilizers, it is recommended to partially replacing chemical fertilizers with CMFE, with the optimal combination of 600 kg·ha−1 chemical fertilizer +300 L·ha−1 CMFE (T3).

NITROGEN FERTILIZATION IN THE DEVELOPMENT OF Brassica oleracea L.

Leaf kale is a crop that is widely consumed today due to the new ways of using it in cooking and its nutritional properties. However, the crop has a high requirement for nitrogen fertilization, so the excessive application of mineral fertilizers causes environmental impacts. Considering the importance of kale and its high nutritional requirement, the objective of this work was to evaluate the effect of organomineral fertilization on the development of kale cv. Butter. The treatments were distributed in randomized blocks, in a 2x4 factorial scheme, referring to two sources of nitrogen (urea and cattle manure) and four doses of fertilizers (0, 50, 100 and 150% of the dose of 120 kg ha-1 of nitrogen ) with three replications and during two growing seasons. The sources used were urea and bovine manure. Plant height, number of leaves, leaf area, stem diameter, fresh and dry mass of shoots were analyzed. The organomineral fertilization positively influenced the development of the aerial part. Cultivation season 1 favored the increase of the evaluated variables with a lower percentage of organomineral used. Greater number of leaves was achieved by using 150% (higher dose) of fertilizers in season 2.

The Coupling Relationship and Driving Factors of Fertilizer Consumption, Economic Development and Crop Yield in China

China has become the largest consumer of chemical fertilizers. The excessive application of chemical fertilizers has resulted in a series of problems including environmental pollution, seriously threatening China’s sustainable development. Therefore, it is highly important to study the factors driving chemical fertilizer consumption. In this study, we used the panel data of 31 provinces in China and the Tapio decoupling model to explore the coupling relationship between fertilizer consumption, economic growth and crop yield increase, build the IPAT-LMDI model, and identify and analyze the factors driving the observed changes. The results show the following: (1) Since 2015, the consumption of chemical fertilizers in most provinces of China has decreased significantly, and the implementation of the zero-fertilizer policy in various regions has generally achieved remarkable results. (2) Since 1980, China’s crop production and economic development have undergone coordinated growth, but the decoupling relationship between chemical fertilizer consumption and economic growth has changed from weak to strong, and the dependence of China’s crop production on chemical fertilizers has gradually been reduced. (3) Fertilizer consumption in China is promoted by factors related to economic level (Pg), crop value (Cval), fertilizer efficiency (Feff), fertilization intensity (Fein), per capita arable land area (Clap) and population size (P), while it is restrained by factors related to science and technology level (Ffag), agricultural population (P1) and industrial structure (Inst). (4) Fertilizer consumption has arrived at its peak in East China, South China and Central China, while there is still room for growth in the western areas; gaps in economic and technological development between different provinces are the main factors affecting changes in fertilizer consumption. Finally, we offer specific suggestions for improving the efficiency of chemical fertilizers from the perspectives of farming modes and science and technology.

Driving factors on accumulation of cadmium, lead, copper, zinc in agricultural soil and products of the North China Plain

The accumulation of heavy metals in agricultural soils concerns food security. By using the Geographical Detector, this study investigated the influence of six types of factors (eleven factors) on the accumulation of Cd, Pb, Cu, Zn in agricultural soil and products of the North China Plain and confirmed the dominant factor. The results showed that heavy metals had accumulated in regional agricultural soils and the accumulation of Cd was severe. The accumulation of heavy metals was significantly influenced by policy factors (the management and reduction in usage of fertilizers and pesticides), fertilization factors (application of organic and chemical fertilizers), pesticide factors (application of herbicide and insecticide) and atmospheric deposition factors (heavy metal concentration in atmospheric deposition). The policy factor dominated the other three types of factors. Atmospheric deposition and the excess application of fertilizers and pesticides directly lead to the accumulation of heavy metals. Due to the high concentrations of heavy metals and abundant application amounts, organic fertilizers have contributed high levels of heavy metals to agricultural soils. This study suggests that formulated fertilization and action plans for pesticide reduction could effectively decrease the accumulation of heavy metals in agricultural soils and products in the study area.

Effects of rotted corn straw on soil environment, yield, and quality of cucumber.

Aiming at solving the problems of soil environment deterioration and the decline of both yield and quality caused by excessive application of chemical fertilizer, we investigated the effects of rotted corn straw on the soil environment of root zone, yield and quality of cucumber with 'Jinyou 35' cucumber as the experimental material. There were three treatments, namely, combined application of rotted corn straw and chemical fertilizer (T1, the total nitrogen fertilizer application were 450 kg N·hm-2, of which 9000 kg·hm-2 rotted corn straw was used as the subsoil fertilizer, and the rest was supplemented with chemical fertilizer), pure chemical fertilizer (T2, the total nitrogen fertilizer application was the same as T1) and no fertilization (control). The results showed that the content of soil organic matter in root zone soil in T1 treatment was much higher, but no difference between T2 treatment and the control, after two continuous plantings in one year. The concentrations of soil alkaline nitrogen, available phosphorus, available potassium of T1 and T2 in cucumber root zone were higher than that in the control. T1 treatment had lower bulk density, but markedly higher porosity and respiratory rate than T2 treatment and the control in root zone soil. The electric conductivity of T1 treatment was higher than that of the control, but significantly lower than T2 treatment. There was no significant difference in pH among the three treatments. The quantity of bacteria and actinomycetes in cucumber rhizosphere soil were the highest in T1, and the lowest in the control. However, the highest quantity of fungi was found in T2. The enzyme activities of rhizosphere soil in T1 treatment were markedly higher than those of the control, whereas those of T2 treatment were significantly lower or had no significant difference relative to the control. The cucumber root dry weight and root activity of T1 were significantly higher than that of the control. The yield of T1 treatment increased by 10.1%, and fruit quality improved obviously. The root activity of T2 treatment was also significantly higher than that in the control. There was no significant difference in root dry weight and yield between T2 treatment and the control. Furthermore, T2 treatment revealed a decrease in fruit quality relative to T1 treatment. These results suggested that the combined application of rotted corn straw and chemical fertilizer could improve soil environment, promote root growth, enhance root activity and improve yield and quality of cucumber in solar-greenhouse, which could be popularized and applied in protected cucumber production.

一次性机械化穴施缓释复合肥对玉米产量和养分吸收的影响

Currently, maize production in China suffers from many problems, such as excessive fertilizer application, inefficient fertilizer use, and insufficient agricultural labour. The effect of one-time mechanical point-applied fertilization of controlled-release compound fertilizer in the root-zone on yield and nutrient uptake was investigated to explore efficient fertilization patterns for fertilizer decrease and yield increase in maize. The selected fertilizer was a controlled-release granular fertilizer (24-6-10 for N-P2O5-K2O) with six treatments in the application program: 1) no fertilizer (CK); 2) application of a one-time banding fertilizer (BDP) 5 cm off the seeds between rows and 10 cm deep; 3) application of a one-time point-applied fertilization (RZF) 5 cm off seed in the row and 10 cm deep; 4) application of a one-time point-applied fertilization (90% RZF) 10% fertilizer reduction 5 cm off seed in the row and 10 cm deep; 5) application of a one-time point-applied fertilization (80% RZF) 20% fertilizer reduction 5 cm off seed in the row and 10 cm deep; 6) application of a one-time point-applied fertilization (70% RZF) 30% fertilizer reduction 5 cm off seed in the row and 10 cm deep. The results showed that RZF increased yield by 5.84% over BDP, and the difference was significant, indicating that mechanized point-applied fertilization of fertilizer can replace manual point-applied fertilization application operations and achieve increased crop yield. The agronomic utilization rate of fertilizer of 12.35% and the bias productivity of 5.31% were higher in RZF than in BDP, and the differences were significant, indicating that one-time mechanical point-applied fertilization in the root zone significantly improved fertilizer utilization and reduced fertilizer loss.

Development of Grooved Belt Type Fertilizer Metering Mechanism for Spot Fertilizer Applicator

Higher risks involved in excess fertilizer application require precise placement of fertilizer in adequate amount in the root zone of the crop. The drawbacks of current fertilizer application techniques (band placement, pellet application, and ring basin method) include over-fertilization, soil acidity, nutritional imbalances, soil structure damage and an increase in bulk density. Development of a spot fertilizer applicator with precise fertilizer metering was planned to address the problem. The physical and mechanical properties of di-ammonium phosphate were determined. A new grooved belt type fertilizer metering mechanism was developed for orchard application using the fertilizer properties determined. The metering mechanism was equipped with a fertilizer box of 100 kg capacity. The torque requirement of metering mechanism was determined using torque transducer to select a DC motor. The maximum torque required was 4.5 N.m at 8 m.min-1 of metering belt speed. An automatic plant detection-based spot fertilizer applicator with developed fertilizer metering mechanism has potential to save about 20% fertilizer compared to band placement along with reduced labour requirement.

Effect of fertilization combination on cucumber quality and soil microbial community.

Due to the lack of scientific guidance on the usage of fertilizer, the overuse of chemical and organic fertilizer is commonly witnessed all over the world, which causes soil degradation and leads to environmental pollution. The effect of fertilizer strategies on soil properties, cucumber nutrients, and microbial community was investigated in this study with the aim to explore an optimized and enhanced fertilizer strategy. There were five fertilizer strategies conducted including CK (no fertilizer), M (cow dung manure only), NPK (chemical fertilizer only), NPKM (chemical fertilizer combined with manure), and DNPKM (30%-reducing chemical fertilizer combined with manure). It was found that different fertilizer strategies significantly affected the soil organic matter and nutrient levels and cucumber production and nutrient contents of the experimental field. Different fertilizer strategies showed dramatic effects on the alpha- and beta-diversity of soil microbial communities. Moreover, NPKM and DNPKM groups could significantly improve the bacterial abundance and fungal diversity. In addition, the structure of microbial communities was significantly changed in the presence of manure, chemical fertilizer, and their combination. Optimized combination of NPK with M improved the abundance of aerobic, biofilm formation-related, and Gram-negative bacteria and suppressed the anaerobic and Gram-positive bacteria. The presence of saprotrophs fungi was enhanced by all fertilizer strategies, especially the plethora of Gymnoascus. The combination of manure with chemical fertilizer could improve the availability of nutrients, and therefore reduce the adverse effects and potential risks induced by excessive fertilizer application. In conclusion, the new fertilization approach can not only meet the growth requirements of cucumber after reduced fertilization, but also protect soil health, which provides a new candidate for the eco-friendly technology to satisfy the topic of carbon neutrality.

A Review on the Agriculture Non-point Source Pollution Research

Agricultural non-point source pollution is an important problem at present. By analyzing the amount and intensity of fertilizer application and the proportion of different types of fertilizer application in the past 10 years, the paper makes clear that the excessive application of fertilizer and the imbalance of fertilizer structure are the main causes of agricultural non-point source pollution.

Effect of Rational Fertilizer for Eggplants on Nitrogen and Phosphorus Pollutants in Agricultural Water Bodies

Excessive fertilizer application in the cropping industry leads to excessive nitrogen and phosphorus in surrounding water bodies, which causes farmers to increase economic cost and damage the environment. To address the problem, we built a crop-soil runoff soil column test system, setting eight fertilizer application levels for eggplants. Then, crop yield, soil fertility and pollutant concentrations in the receiving water bodies were measured. The process of fertilizer application on the water quality of surrounding receiving water bodies and the rationality of fertilizer application were analyzed. The results showed that crop yield, soil fertility, and pollutant concentrations in the receiving water increased with the increase in fertilizer application. The crop yield stabilized when the fertilizer application amount was higher than 0.12 kg/m2; the concentrations of total nitrogen (TN) and total phosphorus (TP) in the water increased significantly with the increase in fertilizer application, where particulate nitrogen (PN) and organic phosphorus (OP) were the key pollutants. In addition, crop growth had an interception effect on pollutant migration. The concentration of pollutants in the water was significantly lower in the late crop growth period (after flowering) than in the early. The crop had the best interception effect on pollutants when the fertilizer application was 0.12 kg/m2. The concentrations of TN and TP in the water were 29.7% and 22.3% after the flowering period, being lower than those before the flowering period. Therefore, a reasonable value of 0.12 kg/m2 is recommended for fertilizer application in this article. It can provide a reference for the fertilization system of eggplant planting in North China and theoretical support for the realization of clean production in small rural watershed planting.

Efficiency Recycling and Utilization of Phosphate from Wastewater Using LDHs-Modified Biochar.

The excessive application of phosphate fertilizers easily causes water eutrophication. Phosphorus recovery by adsorption is regarded as an effective and simple intervention to control water bodies' eutrophication. In this work, a series of new adsorbents, layered double hydroxides (LDHs)-modified biochar (BC) with different molar ratios of Mg2+ and Fe3+, were synthesized based on waste jute stalk and used for recycling phosphate from wastewater. The prepared LDHs-BC4 (the molar ratio of Mg/Fe is 4:1) has significantly high adsorption performance, and the recovery rate of phosphate is about 10 times higher than that of the pristine jute stalk BC. The maximum adsorption capacity of LDHs-BC4 for phosphate was 10.64 mg-P/g. The main mechanism of phosphate adsorption mainly includes electrostatic attraction, ion exchange, ligand exchange, and intragranular diffusion. Moreover, the phosphate-adsorbed LDHs-BC4 could promote mung bean growth, which indicated the recovery phosphate from wastewater could be used as a fertilizer.

Effects of Fertilization and Straw Mulching on Nitrogen and Phosphorus Loss in Chengdu Plain

In recent years, the excessive application of nitrogen and phosphorus fertilizers has caused serious pollution and eutrophication, especially in paddy fields. Accordingly, a two-year (2018-2019) study was conducted at a rice paddy field under different fertilizer application rates and straw mulching in Chengdu Plain. N and P losses through the rainfall and surface runoff in the paddy field were measured under natural rainfall conditions. The results showed that nitrogen mainly existed in the form of ammonium nitrogen, and phosphorus mainly existed in the form of soluble phosphorus in the wet deposition. The wet deposition of nitrogen and phosphorus mainly occurred in June, July, and August. Surface runoff was positively correlated with rainfall, whereas surface runoff nitrogen concentration was inversely correlated with rainfall. The highest runoff losses of TN (4.75 kg·hm-2 in 2018 and 2.68 kg·hm-2 in 2019) were produced by TR3 practice and were 26.73% and 43.32% higher than that of the conventional practice. TN runoff loss was significantly decreased by reducing the rate of N fertilizer (P<0.05). Compared with that in the conventional practice TR1, TR4 reduced the N loss by 36.33% in 2018 and 26.74% in 2019, respectively. Optimized fertilizer TR2 and nitrogen reduction practice TR4 decreased P loss from surface runoff, and high intensity rainfall could reduce the content of granular phosphorus in surface runoff. The surface runoff occurring in July, August, and September contributed mostly to the total N loss, whereas the loss of total P mainly occurred before July. Consequently, the use of balanced fertilizer and decreased nitrogen fertilization amount might be effective strategies to attenuate non-point source pollution in the Chengdu Plain in the paddy fields.

From Agricultural Green Production to Farmers' Happiness: A Case Study of Kiwi Growers in China.

Happiness is the ultimate goal of everyone working and earning wealth. At present, in the vast rural areas of China, the excessive and unscientific application of chemical fertilizers and pesticides is raising serious concerns for environmental protection. The Chinese government has strongly promoted agricultural green production as an alternative to the previous agricultural paradigm that sacrificed the environment. A shift towards agricultural green production has become imperative. However, will it bring "happiness" to farmers who partake in this shift? Using data from 1138 farmers in Shanxi, Northwest China, throughout 2022, this article examines the relationship between the adoption of agricultural green production and farmers' happiness. The empirical findings indicate that the adoption of agricultural green production can considerably increase farmers' happiness and that the more types of agricultural green technologies that are implemented, the greater the happiness of farmers. Further mediating effect analysis suggests that this mechanism occurs through raising the absolute and relative income, mitigating agricultural pollution, and elevating the social status. The findings shed new light on the effect of farmers' economic behavior on their happiness and underline the necessity of implementing relevant policies.

Combination of Aspergillus niger MJ1 with Pseudomonas stutzeri DSM4166 or mutant Pseudomonas fluorescens CHA0-nif improved crop quality, soil properties, and microbial communities in barrier soil.

Soil salinization and acidification seriously damage soil health and restricts the sustainable development of planting. Excessive application of chemical fertilizer and other reasons will lead to soil acidification and salinization. This study focus on acid and salinized soil, investigated the effect of phosphate-solubilizing bacteria, Aspergillus niger MJ1 combined with nitrogen-fixing bacteria Pseudomonas stutzeri DSM4166 or mutant Pseudomonas fluorescens CHA0-nif on crop quality, soil physicochemical properties, and microbial communities. A total of 5 treatments were set: regular fertilization (T1), regular fertilization with MJ1 and DSM4166 (T2), regular fertilization with MJ1 and CHA0-nif (T3), 30%-reducing fertilization with MJ1 and DSM4166 (T4), and 30%-reducing fertilization with MJ1 and CHA0-nif (T5). It was found that the soil properties (OM, HN, TN, AP, AK, and SS) and crop quality of cucumber (yield production, protein, and vitamin C) and lettuce (yield production, vitamin C, nitrate, soluble protein, and crude fiber) showed a significant response to the inoculated strains. The combination of MJ1 with DSM4166 or CHA0-nif influenced the diversity and richness of bacterial community in the lettuce-grown soil. The organismal system-, cellular process-, and metabolism-correlated bacteria and saprophytic fungi were enriched, which were speculated to mediate the response to inoculated strains. pH, OM, HN, and TN were identified to be the major factors correlated with the soil microbial community. The inoculation of MJ1 with DSM4166 and CHA0-nif could meet the requirement of lettuce and cucumber growth after reducing fertilization in acid and salinized soil, which provides a novel candidate for the eco-friendly technique to meet the carbon-neutral topic.

A Meta-Analysis Study on the Use of Biochar to Simultaneously Mitigate Emissions of Reactive Nitrogen Gases (N2O and NO) from Soils

Nitrous oxide (N2O) and nitric oxide (NO) are detrimental reactive gaseous oxides of nitrogen. Excessive application of nitrogen fertilizers in cropping systems has significantly increased the emissions of these gases, causing adverse environmental consequences. Previous studies have demonstrated that biochar amendment can regulate soil-N dynamics and mitigate N losses, but they lacked simultaneous assessments of soil N2O and NO emissions. Thus, the factors influencing the emissions of nitrogen oxides are still unclear. Therefore, this study examined the impact of biochar application on simultaneous N2O and NO emissions based on 18 peer-reviewed papers (119 paired observations). A machine learning model (boosted regression tree model) was adopted to assess the potential influencing factors, such as soil properties, biochar characteristics, and field management conditions. The addition of biochar reduced N2O and NO emissions by 16.2% and 14.7%, respectively. Biochar with a high total carbon content and pH, from woody or herbaceous feedstock, pyrolyzed at a high temperature, applied at a moderate rate and to soil with a high-silt content, a moderate pH, and coarse texture, could simultaneously reduce soil N2O and NO emissions. Biochar amendment, thus, has the potential to lower the environmental impact of crop production. Furthermore, the influence of soil properties, biochar characteristics, and field management should be considered in the future to enhance the efficacy of biochar.

Combined Effects of Indigenous Arbuscular Mycorrhizal Fungi (AMF) and NPK Fertilizer on Growth and Yields of Maize and Soil Nutrient Availability

The excessive application of mineral fertilizers in maize cultivation leads to progressive soil contamination in the long term and increases the cost of production. An alternative to reduce over-fertilization is to perform a partial replacement with microbes that promote nutrition and growth, such as Arbuscular Mycorrhizal Fungi (AMF). A pot experiment which was followed by two field experiments was performed with and without the application of indigenous AMF in combination with five nitrogen–phosphorus–potassium (NPK) fertilization rates (100% NPK = N120P60K60; 75% NPK = N90P45K45; 50% NPK = N60P30K30; 25% NPK = N30P15K15; control = N0P0K0). The objective was to investigate whether the soil application of indigenous mycorrhizal fungi inoculum combined with NPK fertilization can provide higher maize yields and soil-available N, P, and K than chemical fertilization can alone. The greenhouse results showed that the application of AMF with a 50% NPK treatment significantly increased the plant’s growth, root colonization, leaf chlorophyll content, and N, P, and K tissue content. The results from the field conditions showed that there was a highly significant yield after the treatment with AMF + 50% NPK. The study also revealed that mycorrhizal fungi inoculation increased the available soil N and P concentrations when it was combined with a 50% NPK dose. This suggests that the inoculation of fields with AM fungi can reduce the chemical fertilizer application by half, while improving soil chemistry. The results suggested that AMF inoculation can be used in integrated soil fertility management strategies.

An apple NITRATE REDUCTASE 2 gene positively regulates nitrogen utilization and abiotic stress tolerance in Arabidopsis and apple callus

Nitrogen (N) is an essential element that plays an important role in crop biomass accumulation and quality formation. Increased crop yield is relied on excessive application of fertilizers, which usually leads to environmental pollution and unsustainable development. Thus, identification and characterization of genes involved in promoting nitrogen use efficiency is of high priority in crop breeding. The activity of nitrate reductase (NR) plays a critical role in nitrogen metabolism. In model plant Arabidopsis, NITRATE REDUCTASE 2 (NIA2), one of the two NRs, is responsible for about 90% of the NR activity. In this study, MdNIA2 gene in apple (Malus domestica) genome was screened out and identified by using AtNIA2 as bait. Phylogenetic analysis revealed that MdNIA2 had the closest evolutionary relationship with MbNIA from Malus baccata. Ectopic expression of MdNIA2 in Arabidopsis elevated the nitrogen use efficiency and increased root hair elongation and formation, resulting in promoted plant growth. Furthermore, the overexpression of MdNIA2 improved salt and drought tolerance in transgenic Arabidopsis and improved the salt tolerance of transgenic apple callus, and MdNIA2-reagualted NO metabolism might contribute to the abiotic stress tolerance. Overall, our data indicate the critical role of MdNIA2 in regulating nitrogen utilization efficiency and abiotic stress responses.

Effects of nitrogen input on soil bacterial community structure and soil nitrogen cycling in the rhizosphere soil of Lycium barbarum L.

Lycium barbarum L., goji berry, is a precious traditional Chinese medicine and it is homology of medicine and food. Its growth is heavily dependent on nitrogen. The use of chemical fertilizers has significantly promoted the yield of goji berry and the development of the L. barbarum L. industry. However, crop plants are inefficient in the acquisition and utilization of applied nitrogen, it often leads to excessive application of nitrogen fertilizers by producers, which cause negatively impact to the environment ultimately. The exploration of an interaction model which deals with crops, chemical fertilizers, and rhizosphere microbes to improve nitrogen use efficiency, is, therefore, an important research objective to achieve sustainable development of agriculture greatly. In our study, we explored the effects of nitrogen input on soil microbial community structure, soil nitrogen cycling, and the contents of nutrients in L. barbarum fruits. The structure and composition of the bacterial community in the rhizosphere soil of L. barbarum were significantly different under different nitrogen supply conditions, and high nitrogen addition inhibited the diversity and stability of bacterial communities. Low nitrogen input stimulated the relative abundance of ammonia-oxidizing bacteria (AOB), such as Nitrosospira, catalyzing the first step of the ammonia oxidation process. The results of the GLMM model showed that the level of nitrogen fertilizer (urea) input, the relative abundance of AOB, the relative abundance of Bradyrhizobium, and their combinations had significant effects on the soil nitrogen cycling and contents of nutrients in L. barbarum fruits. Therefore, we believe that moderately reducing the use of urea and other nitrogen fertilizers is more conducive to improving soil nitrogen use efficiency and Goji berry fruit quality by increasing the nitrogen cycling potential of soil microorganisms.

Weed Dynamics, Productivity and Profitability of Transplanted Aman Rice as Influenced by Integrated Nutrient Management and Weeding Regime

The excessive and improper application of fertilizers is the key factor contributing to nutrient losses to the environment and a decrease in the fertility of the soil. Also, using the wrong herbicide, applying higher than the recommended rate, or improper timing of application can cause crop damage. These factors adversely affect soil productivity and environmental stability. There is thus a need to expand an effective and inexpensive integrated nutrient management and weed control practice for acquiring better yields and profit from rice. The aim of the study was to find out the effect of six integrated nutrient management i.e., BRRI Recommended Dose (RD) of chemical fertilizer, 50% RD + 5 t of cowdung ha-1, 50% RD + 10 t of cowdung ha-1, 50% RD + 2.5 t of poultry manure ha-1, 50% RD + 5 t of poultry manure ha-1, USG 1.8 g 4 hills-1 + TSP, MoP, Gypsum and ZnSO4 @RD along with four weeding regimes i.e., control (no weeding), pre-emergence herbicide followed by one hand weeding at 30 DAT, early post-emergence herbicide followed by one hand weeding at 30 DAT, pre-emergence herbicide followed by early post-emergence herbicide on weed control, rice productiveness, and profitability. Our findings suggest that the application of 50% of the RD of chemical fertilizer + 5 t of poultry manure ha-1 with the application of pre-emergence herbicide followed by early post-emergence herbicide enhances weed suppression and provides higher rice productivity and profitability and can be practiced for the maximization of the yield and net return of transplanted aman rice.