Nitrogen Partial Productivity Research Articles

Response of cotton growth, yield, and water and nitrogen use efficiency to nitrogen application rate and ionized brackish water irrigation under film-mulched drip fertigation.

The presence of brackish water resources is significant in addressing the scarcity of freshwater resources, particularly in the Xinjiang region. Studies focused on reducing adverse effect of brackish water irrigation based on using ionized brackish water, as well as on investigating its effects on fibre and oil plant production processes, remain incipient in the literature. Some benefits of this technique are the optimization of the quality and quantity of irrigation water, economy of water absorbed by the plants, improvement in the vegetative growth and productivity compared to irrigation using conventional brackish water. Thus, the aim of the current study is to assess the effect of different nitrogen application rates on soil water and salinity, cotton growth and water and nitrogen use efficiency. The experimental design consisted of completely randomized design with two water types (ionized and non-ionized) and six nitrogen application rates with four replications. Irrigation conducted with ionized brackish water and different nitrogen application rates had significant effect on the plant height, leaf area index, shoot dry matter, boll number per plant and chlorophyll content. The study also demonstrated significant effects of ionized brackish water on soil water content and soil salinity accumulation. The highest cotton production was achieved with the use of 350 kg·ha-1 of ionized brackish water for irrigation, resulting in an average increase of 11.5% compared to the use of non-ionized brackish water. The nitrogen application exhibits a quadratic relationship with nitrogen agronomic use efficiency and apparent nitrogen use efficiency, while it shows a liner relationship with nitrogen physiological use efficiency and nitrogen partial productivity. After taking into account soil salinity, cotton yield, water and nitrogen use efficiency, the optimal nitrogen application rate for ionized brackish water was determined to be 300 kg·ha-1. It is hoped that this study can contribute to improving water management, reducing the environmental impact without implying great costs for the producer.

Appropriate Water and Nitrogen Regulation Improves the Production of Wolfberry (Lycium barbarum L.)

Wolfberry (Lycium barbarum L.) production in arid and semi-arid areas is drastically affected by the low utilization rate of soil and water resources and the irrational application of water and nitrogen fertilizers. Thus, this study explored a high-yielding, high-quality, and efficient irrigation and nitrogen regulation model to promote the production efficiency of wolfberry and rational utilization of water and land resources in arid and semi-arid areas. We compared and analyzed the effects of different soil water treatments (the upper and lower limits of soil water were estimated as the percentage of soil water content to field water capacity (θf), with the following irrigation regimen: adequate irrigation (W0, 75–85% θf), mild water deficit (W1, 65–75% θf), moderate water deficit (W2, 55–65% θf), and severe water deficit (W3, 45–55% θf)) and nitrogen levels (no nitrogen (N0, 0 kg·ha−1), low nitrogen (N1, 150 kg·ha−1), moderate nitrogen (N2, 300 kg·ha−1), and high nitrogen (N3, 450 kg·ha−1)) on the growth, physiology, and production of wolfberry. The results showed that water regulation, nitrogen application level, and their interaction significantly affected plant height and stem diameter growth amount (p < 0.05). Additionally, the relative chlorophyll content of wolfberry leaves first increased and then decreased with increasing nitrogen levels and water deficit. The average net photosynthetic rate (Pn), stomatal conductance (gs), intercellular carbon dioxide concentration, and transpiration rate (Tr) reached the highest values in plants exposed to W0N2 (19.86 μmmol·m−2·s−1), W1N1 (182.65 mmol·m−2·s−1), W2N2 (218.86 μmol·mol−1), and W0N2 (6.44 mmol·m−2·s−1) treatments, respectively. Pn, gs, and Tr were highly correlated with photosynthetically active radiation and water vapor pressure difference (goodness-of-fit: 0.366–0.828). Furthermore, water regulation and nitrogen levels exhibited significant effects on the yield and water- (WUE), and nitrogen-use efficiency (NUE) (p < 0.01), and their interactions exhibited significant effects on the yield, WUE, and nitrogen partial productivity of wolfberry plants (p < 0.05). Moreover, the contents of total sugar, polysaccharides, fats, amino acids, and proteins were the highest in W1N2, W1N2, W1N2, W2N3, and W0N2 treatments, respectively, which were increased by 3.32–16.93%, 7.49–54.72%, 6.5–45.89%, 11.12–86.16%, and 7.15–71.67%, respectively. Under different water regulations (except for the W3 condition) and nitrogen level treatments, the net income and input–output ratio of wolfberry were in the order W1 > W0 > W2 > W3 and N2 > N3 > N1 > N0. The TOPSIS method also revealed that the yield, quality, WUE, NUE, and economic benefits of wolfberry improved under the W1N2 treatment, suggesting that WIN2 might be the most suitable irrigation and nitrogen regulation model for wolfberry production in regions with scarce land and water resources such as the Gansu Province and areas with similar climate.

Rational Utilization of Sediment Resources Improves Rice Yield and Nitrogen Use Efficiency under Salt Stress

Soil salinization negatively affects rice growth and yield; however, how different sludge sources regulate rice growth and yield under salt stress was rarely investigated. This study evaluated the performance of two salt-tolerant rice cultivars, Chaoyou 1000 and Longliangyou 506, grown in two sediment sources, pond sediment (PS) and river sludge (RS), under salt stress (56 ds m−1 brine irrigation) with conventional soil (CS) used as the control. The results showed that the rice yield under the PS and RS treatments was enhanced by 51.0% and 43.6% as compared with CS, respectively, owing to an improvement in spikelet per panicle, 1000-grain weight, dry matter accumulation, and the chlorophyll content in both rice cultivars. Compared with CS, the total nitrogen accumulation, nitrogen grain production efficiency, nitrogen harvest index, and nitrogen partial productivity under the PS and RS treatments were increased by 18.9–28.9%, 17.0–20.6%, 7.2–16.6%, and 43.8–50.9%, respectively. Moreover, rice grown in PS and RS showed higher activities of nitrogen metabolism-related enzymes (nitrate reductase, glutamine synthetase, and glutamate synthetase) at the heading stage and higher K+ and K+/Na+ contents in the leaves. Overall, a balanced utilization of sediment resources (especially pond sediment) can effectively alleviate salt stress and improve the yield and nitrogen use efficiency in rice.

Effects of Different Nitrogen Allocation Ratios and Period on Cotton Yield and Nitrogen Utilization

Choosing the proper fertilizer regime for a crop in a given location remains challenging to increase yield, profitability, environmental growth protection, and sustainability. However, the nutrient demand characteristics of cotton in the North China Plain are different at various growth stages. Therefore, we choose the local superior cotton variety (Lumian 532) with high yield as the material, in the present study, we assessed the cotton yield, biomass accumulation and distribution, nitrogen absorption and utilization efficiency, and other parameters by setting four nitrogen allocation ratios (3:5:2, 0:10:0, 3:7:0, and 0:7:3) when the nitrogen application rates were 0, 150, 220, and 300 kg hm−2. The results showed that when the nitrogen application rate was 300 kg hm−2, the growth index, biomass, nitrogen content, and yield of Lumian 532 were the highest, while the nitrogen partial productivity (12.2 and 12.8) was the lowest. When the nitrogen application rate was 220 kg hm−2 and the nitrogen allocation ratio was 3:5:2, the agronomic nitrogen use efficiency (3.2 and 3.5) and nitrogen physiological (24.8 and 25.0) was achieved. When the nitrogen application rate was 150 kg hm−2, the nitrogen partial productivity (20.6 and 20.9) was the highest. In conclusion, the biomass accumulation and distribution, nitrogen use efficiency, yield, and yield composition of Lumian 532 could be effectively regulated by appropriate nitrogen application rate and nitrogen allocation ratio. Therefore, to optimize the yield and improve the nitrogen use efficiency, the optimal nitrogen application rate of Lumian 532 was 220 kg hm−2, and the optimal nitrogen allocation ratio was 3:5:2 in the North China Plain. The results provided practical basis for nutrient demand, cotton yield and ecological protection in different growth stages of cotton in North China Plain.

Drip fertilization improve water and nitrogen use efficiency by optimizing root and shoot traits of winter wheat.

Proper irrigation and fertilization measures can not only improve water and fertilizer utilization efficiency, but also have important significance in ensuring agricultural environment security and sustainable development. A field experiment was conducted to determine the optimal drip fertilization measure of winter wheat and explain its mechanism by analyzing the physiological and ecological characteristics and utilization efficiency of water and nitrogen under different irrigation and fertilization methods. The plants were treated with three irrigation and fertilization methods: the traditional irrigation and fertilization method (CK), surface drip fertilization (I1) and underground drip fertilization (I2). The results demonstrated that different irrigation methods had various effects on population and physiological characteristics of wheat. The plant height, leaf area and tiller number of I1 were significantly higher than those of CK during the whole growth period. I2 decreased plant height, leaf area and tiller number at jointing stage, but at flowering stage, the leaf area of I2 t was significantly higher than that of CK. Different irrigation methods also affected the root distribution of wheat. At flowering stage, I1 had lower root biomass than CK in all soil layers. The upper root system of I2 was smaller, but the deep root system was larger compared with the control. I1 and I2 had lower total root weight and higher shoot biomass compared to CK, so their root-shoot ratio decreased significantly. I1 and I2 increased and instantaneous water use efficiency (IWUE) by increasing the photosynthetic rate (Pn) and reducing transpiration rate (Tr) at the flowering stage, while I2 had a similar Pn to I1, but reduced Tr, resulting in a higher IWUE than I1. Both I1 and I2 also increased root efficiency, root activity, and Fv/Fm of wheat at the late growth stage, promoting accumulated dry matter after flowering (ADM) and pre-flowering dry matter remobilization (DMR), leading to a significant increase in grain yield. In addition, I1 and I2 had significantly higher water productivity (WP), irrigation water productivity (IWP), nitrogen partial productivity (NPP) and nitrogen agronomic efficiency (NAE) than CK, especially I2 had the highest IWP, WP, NPP and NAE. These findings highlight the potential benefits of drip fertilization in promoting sustainable wheat production and elucidate the mechanism by which it promotes efficient use of water and fertilizer.

Effects of Drip Irrigation and Fertilization Frequency on Yield, Water and Nitrogen Use Efficiency of Medium and Strong Gluten Wheat in the Huang-Huai-Hai Plain of China

Drip irrigation can reduce water and fertilizer use; however, the frequency of topdressing required for drip irrigation for wheat in the Huang-Huai-Hai region is still unclear. Through two continuous wheat season field experiments, yield related traits under traditional surface irrigation (border irrigation) and three drip fertilization frequencies (DF2, DF3, DF4, that was, topdressing water and fertilizer twice, three or four times in the same way during the growth period) of three wheat cultivars (Jimai 22, Jimai 20, Shiluan 02-1) were studied. Increasing the frequency of drip irrigation fertilization could prolong the time of high-level photosynthesis, increase the dry matter distribution amount (DMDA) of stems and leaves, and add the weight of 1000 grains; it could increase the DMDA and nitrogen distribution amount (NDA) of the stems, leaves, and grains of Jimai 22, forming higher harvest index (HI) and nitrogen harvest index (NHI), but could reduce the DMDA of the grains of Jimai 20 and Shiluan 02-1, increasing NDA, reducing the harvest index but forming a higher nitrogen harvest index. The increase in drip irrigation fertilization frequency can improve protein content, increase grain number per spike, decrease spike number, improve the yield of medium gluten wheat, and improve nitrogen partial productivity and water use efficiency, while strong gluten wheat has a decrease in yield, nitrogen partial productivity, and water use efficiency. In summary, medium gluten wheat is more suitable for higher fertilization frequency in the Huang-Huai-Hai wheat region, while strong gluten wheat is the opposite.

Differentiation in Nitrogen Transformations and Crop Yield as Affected by Tillage Modes in a Fluvo-Aquic Soil

Nitrogen is a vital element for soil fertility and crop productivity. The transformation of nitrogen is directly affected by tillage practices for the disturbing soil. The characteristics of different nitrogen forms under different tillage modes are still unclear. A 3-year cycle tillage experiment was carried out to assess the combination of rotary tillage (RT), deep tillage (DT), and shallow rotary tillage (SRT) on nitrogen transformation and distribution, wheat yield and nitrogen balance in fluvo-aquic soil from Huang-Huai-Hai Plain in China. The results showed the rotation tillage cycle with deep tillage in the first year increased the total nitrogen (TN), and the main nitrogen form content in 0-30 cm compared with continued rotary tillage (RT-RT-RT). Moreover, the nitrate (NO3--N) and ammonium nitrogen (NH4+-N) content were improved in 20-40 cm by deep tillage practice with the highest value as 39.88 mg kg-1 under DT-SRT-RT. The time, tillage, and depth significantly affected the different nitrogen forms, but there was no effect on dissolved organic carbon (DON) and soil microbial biomass nitrogen (SMBN) by the interaction of time and tillage. Moreover, compared with RT-RT-RT, the rotation tillage promoted the spike number and kernels per spike of wheat, further increasing the wheat yield and nitrogen partial productivity, and with a better effect under DT-SRT-RT. The NO3--N and NH4+-N trended closer and positively correlated with wheat yield in 0-40 cm in 2019. The rotation tillage with deep tillage improved the different forms of nitrogen in 0-30 cm, wheat yield, and nitrogen partial productivity, and decreased the apparent nitrogen loss. It was suggested as the efficiency tillage practice to improve nitrogen use efficiency and crop yield in this area.

Controlled-release urea application and optimized nitrogen applied strategy reduced nitrogen leaching and maintained grain yield of paddy fields in Northwest China.

Nitrogen loss from paddy fields contributes to most of the nitrogen pollution load in the Ningxia Yellow River irrigation area, threatening the water quality of the Yellow River. Consequently, optimizing the nitrogen management practices in this area is essential, which can maintain paddy grain productivity and reduce nitrogen loss simultaneously. Five treatments with different nitrogen application rates and nitrogen fertilizer types were set in this study, including conventional urea application with zero nitrogen application rate (CK, 0kg hm-2), nitrogen expert-based fertilization application strategy (NE, 210kg hm-2), optimized nitrogen fertilizer application strategy recommended by local government (OPT, 240kg hm-2), and farmer's experience-based nitrogen fertilizer application strategy (FP, 300kg hm-2), and controlled-release urea application (CRU, 180kg hm-2). The data from one growth season field experiment in 2021 revealed the dynamics of nitrogen concentration, paddy yield and its nitrogen uptake characteristic, and nitrogen balance in the paddy field under different nitrogen application practices. Most nitrogen leaching was observed during the seedling and tillering stages in the form of nitrate nitrogen (NO3 -N). Compared with the FP, the CRU and OPT significantly reduced the nitrogen concentrations of total nitrogen (TN), ammonium nitrogen (NH4 +-N), and NO3 -N in the surface and soil water and reduced the nitrogen leaching at 100cm soil depth. Meanwhile, the paddy grain yield in CRU (7737kg hm-2) and OPT (7379kg hm-2) was not significantly decreased compared with FP (7918kg hm-2), even though the nitrogen uptake by grain and straw was higher in FP (135kg hm-2) than in other treatments (52.10~126.40 kg hm-2). However, the grain yield in NE (6972kg hm-2) was decreased compared with the FP. The differences in grain yield among these treatments were mainly attributed to the ear number and grain number changes. Also, the highest nitrogen use efficiency (40.14%), apparent nitrogen efficiency (19.53kg kg-1), and nitrogen partial productivity (43.98kg kg-1) were identified in CRU than in other treatments. Considering increased grain yield and reducing nitrogen loss in the paddy field simultaneously, the treatments of CRU (i.e., 180kg hm-2 nitrogen application rate with controlled-release urea) and OPT (i.e., 240kg hm-2 nitrogen application rate with conventional urea) were recommended for nitrogen fertilizer application in the study area.

Impact of Organic and Chemical Nitrogen Fertilizers on the Crop Yield and Fertilizer Use Efficiency of Soybean–Maize Intercropping Systems

The effect of the mixture (1:1) of chemical and organic nitrogen (N) fertilizer on crop yield quality and N fertilizer use efficiency remains elusive. A nitrogen field experiment was conducted in the growing seasons of 2020 and 2021 to investigate the effects of the mixture of chemical and organic N fertilizer on the crop yield, crop quality and nitrogen fertilizer use efficiency in a maize–soybean intercropping system in China. Four treatments applied at 150 kg N ha−1 were used: no nitrogen fertilizer (CK), chemical N fertilizer (ChemF), mixture (1:1) of chemical and organic N fertilizer (ChemF + OrgF) and organic N fertilizer (OrgF). The results showed that the yield and aboveground N accumulation of both soybean and maize increased with the application of fertilizer. The ChemF + OrgF treatment had lower maize and soybean seed yields than for ChemF treatment, but higher than the other two treatments in both years, and the maize yield of the (ChemF + OrgF) treatment was significantly higher (14.9%) in 2021 than 2020. Yields were significantly positively correlated with aboveground N accumulation and fertilizer use efficiency, measured using the nitrogen partial productivity (NPP), nitrogen agronomic efficiency (NAE) and nitrogen fertilizer recovery rate (NFRR). The protein content tended to increase and the oil content tended to decrease under (ChemF + OrgF) applications in soybeans. The (ChemF + OrgF) treatment had the lowest starch content in maize. There was no significant difference in the nitrogen harvest index among treatments, while the NPP, NAE and NFRR were the highest for the application of chemical N fertilizer and significantly decreased with the addition of organic N fertilizer. We conclude that the mixture (1:1) of chemical and organic N fertilizer increased the seed yield and quality of maize, but only the seed yield of soybean.

Effects of nanobubble in subsurface drip irrigation on the yield, quality, irrigation water use efficiency and nitrogen partial productivity of watermelon and muskmelon

Effects of nanobubble in subsurface drip irrigation on the yield, quality, irrigation water use efficiency and nitrogen partial productivity of watermelon and muskmelon

Matter Production Characteristics and Nitrogen Use Efficiency under Different Nitrogen Application Patterns in Chinese Double-Cropping Rice Systems

Panicle-stage nitrogen fertilizer is popular in parts of China due to its higher nitrogen recovery efficiency compared to basal and tiller nitrogen. However, the effect of conversion from basal to panicle-stage nitrogen on matter production, grain yield, and nitrogen use efficiencies (NUE) in Chinese double-cropping rice systems remains largely unknown. Here, we elucidate the effect by using two types of one-time basal nitrogen patterns (A and B), three panicle-N allocation patterns (C, D, and E), and the local conventional patterns (CK). The two-year experiment demonstrates that E (basal/tiller/spikelet-promoting /spikelet-developing nitrogen = 0:4:3:3) produced the greatest annual grain yield, nitrogen agronomic efficiency, and nitrogen partial productivity. The annual dry matter weight and nitrogen increment of panicle, nitrogen transportation of stems contributes the most to annual yield and NUE. Furthermore, the yield increase could be attributed to the higher effective panicles, plant dry matter weight at tillering, and net photosynthesis rate at heading. Moreover, years and varieties affect the yield in different N treatments. The improvement in the net photosynthesis rate at the milk stage also significantly increases nitrogen recovery efficiency. These findings suggest that it is worth paying attention to the rational ratio of tillering to panicle fertilizer without applying a base fertilizer, to synchronously increase the grain yield, NUE in Chinese double-cropping rice systems.

Effects of side deep placement of nitrogen on rice yield and nitrogen use efficiency

<p indent=0mm>Lateral deep fertilization is an efficient, high-quality, and safe cultivation technology of rice mechanical transplanting. In order to improve the technical system of lateral deep fertilization, we investigated the effects of different fertilization methods on rice yield and nitrogen use efficiency under the condition of lateral deep fertilization. In this study, Nanjing 9108 and Nanjing 5718, the representative varieties of quality and delicious rice of Jiangsu, were used as materials. Four different lateral deep fertilization methods were arranged, including 100% base fertilizer side deep application FM1 (fertilization method 1), 70% base fertilizer side deep application + 30% tillering fertilizer FM2 (fertilization method 2), 70% base fertilizer side deep application + 30% panicle fertilizer FM3 (fertilization method 3), and 35% base fertilizer side deep application + 35% tillering fertilizer + 30% panicle fertilizer FM4 (fertilization method 4). In addition, the conventional fertilization method and no nitrogen treatment were added. The effects of different treatments on rice yield, leaf area index, photosynthetic potential, dry matter accumulation, population growth rate, and nitrogen use efficiency were compared. The results revealed that the yield of FM3 and FM4 were higher than those of other treatments. The main reason was that the spikelet number of the population was significantly higher than that of other treatments on the basis of stable panicle number. The leaf area index and dry matter accumulation of FM3 treatment were higher in the middle and late growth stages, especially from heading to maturity stage. Nitrogen accumulation of FM3 was less before jointing stage, but nitrogen accumulation after jointing stage and the total nitrogen uptake during the whole growth period were significantly higher than those of other treatments. Moreover, the nitrogen agronomic utilization rate, nitrogen physiological utilization rate, nitrogen absorption utilization rate, and nitrogen partial productivity of FM3 were significantly higher than those of the other treatments. At the same time, compared with CFM and FM4, FM3 can reduce fertilization times by 1–2 times, save labor and cost, and is conducive to large-scale production. It is a high-yield, simple and efficient fertilization method for rice.

Effects of deep ploughing during the fallow period and soil moisture-based furrow sowing on water and nitrogen utilization of dryland wheat.

To understand the effects of deep ploughing during the fallow period and soil moisture-based furrow sowing on the utilization of water and nitrogen in dryland wheat, a field experiment following split-plot design was carried out from 2016 to 2018 in Wenxi County of Shanxi Province, with deep ploughing during the fallow period and no-tillage as main plots and soil moisture-based furrow sowing and drilling sowing as sub-plots. The results showed that, compared with no-tillage treatment, deep ploughing during the fallow period significantly increased soil water storage efficiency (by 38.3%-42.2%), soil water consumption (by 9.2%-13.2%), and nitrogen accumulation in each growth period, which in turn increased the yield by 7.1%-12.0%, annual water use efficiency by 5.5%-14.0%, nitrogen fertilizer absorption efficiency by 4.4%-10.3%, and nitrogen fertilizer partial productivity by 7.1%-12.0%. Compared with the treatment of drilling sowing, the soil moisture-based furrow sowing increased the total water consumption during the growth period (by 2.0%-4.8%) and nitrogen accumulation in each growth period, increased the yield by 6.8%-12.4%, water use efficiency during the growth period by 4.5%-7.2%, nitrogen absorption efficiency by 4.4%-10.3%, nitrogen partial productivity by 6.9%-12.4%. In conclusion, deep ploughing during the fallow period and soil moisture-based furrow sowing in dryland wheat could promote the storage and utilization of natural precipitation, increase plant nitrogen accumulation, and facilitate high wheat yield.

Effects of water-nitrogen coupling on photosynthetic characteristics, yield, water and nitrogen use efficiency for mountain apple trees under surge-root irrigation in Northern Shaanxi area of China.

Taking 7-year-old apple trees (Hanfu) as the test material, an experiment with three irrigation levels including high water (W1, 85%-100%θf, θf was the field water holding capacity), medium water (W2, 70%-85%θf) and low water (W3, 55%-70%θf), and three nitrogen application levels, high (N1, 600 kg·hm-2), medium (N2, 400 kg·hm-2) and low (N3, 200 kg·hm-2), was conducted to investigate the effects of water and nitrogen coupling on photosynthetic characteristics, yield and water and nitrogen utilization of apple trees in mountainous areas under surge-root irrigation (SRI). The results showed that the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (gs), intercellular CO2 concentration (Ci), leaf instantaneous water use efficiency (WUEi) of apple trees leaves decreased with decreasing nitrogen application rates under the same irrigation amount, but Ci increased. Under the same nitrogen application rate, foliar Pn, Tr, gs and WUEi decreased with decreasing irrigation amount, but Ci increased. The daily average values of Pn and Tr under W1N1 treatment were the largest, while W2N2 treatment had the largest WUEi. Apple yield, irrigation water use efficiency (IWUE) and nitrogen partial productivity (NPFP) were significantly affected by irrigation and nitrogen application. The W2N2 treatment had the highest yield (26761 kg·hm-2). IWUE increased significantly with the decreasing irrigation and the increasing nitrogen application, while NPFP increased significantly with the increases of irrigation and the decreases of nitrogen application. Results of the regression analysis showed that the combination of irrigation and nitrogen application was closest to W2N2 treatment when yield and IWUE got the optimal solution. Therefore, W2N2 treatment was the best combination mode of water and nitrogen application for apple under SRI in Northern Shaanxi mountain area.

Effects of basic application of chlorocholine chloride combined with nitrogen fertilizer on nitrogen use of summer maize in North China Plain.

To clarify the effects of combined applications of chlorocholine chloride (CCC) and nitrogen fertilizer (CN) on nitrogen metabolism and nitrogen use efficiency of summer maize, we conducted a field experiment in Xinxiang experimental station of Chinese Academy of Agricultural Sciences in 2018 and 2019, with four nitrogen application rates (0, 62.5, 125 and 187.5 kg·hm-2), and two maize varieties of Jingnongke 728 (JNK728) and Zhongdan 909 (ZD909). The results showed that across the two years CN-CCC increased maize yield by 7.7% and 5.0% under the nitrogen application rates of 62.5 kg·hm-2 and 125 kg·hm-2, respectively. CN-CCC increased the contents of nitrate reductase, glutamine synthetase, glutamate synthetase and soluble protein, and finally promoted nitrogen metabolism. Under the low and middle nitrogen application conditions (62.5 kg·hm-2 and 125 kg·hm-2), plant nitrogen content of JNK728 and ZD909 increased by 17.6% and 30.3%, grain nitrogen content increased by 10.3% and 17.4%, nitrogen partial productivity, agronomic efficiency of applied nitrogen, recovery efficiency of applied nitrogen, nitrogen use efficiency increased by 10.0%, 15.7%, 23.3%, 24.8% and 5.7%, 15.0%, 49.9%, 71.7%, respectively. In conclusion, appropriate basic application of CN-CCC could enhance nitrogen metabolism, increase nitrogen use efficiency and grain yield of summer maize. Our results showed that CCC combined basic nitrogen application of 125 kg·hm-2 had the best effect.

Effects of controlled release fertilizer ratio on yield formation and nitrogen absorption and utilization of late-maturing medium &amp;lt;italic&amp;gt;japonica&amp;lt;/italic&amp;gt; rice under different mechanized cultivation methods

<p id="C3">Rice cultivars of Nanjing 9108 with good taste quality was adopted as material under the pure nitrogen condition of 270 kg hm^-2in this study. Rice was cultivated with two methods including mechanical transplanting with pothole seedlings (MT) and mechanical transplanting with carpet seedlings (MC). Controlled-release fertilizer and quick-acting nitrogen fertilizer were mixed at a ratio of 5:5. Controlled-release fertilizer was mixed from four different release periods (40, 80, 100, and 120 days) at a ratio of 1:4 to form three mixing modes (40+80, 40+100, and 40+120). Conventional urea split fertilization (CK) was used as a control, and the effects of different controlled-release fertilizer ratios on yield formation and nitrogen accumulation of high-quality <italic>japonica</italic> rice were studied. Under the same fertilizer treatment, compared with mechanical transplanting with carpet seedlings (MC), the two-year yield of mechanical transplanting with pothole seedlings (MT) was significantly increased by 3.9% and 4.9%, respectively. The reason was that the transplanting of pothole seedling machine could improve the accumulation of photosynthetic substances in the middle and late stages and obtain larger panicle type with higher grain number per panicle, seed setting rate, and 1000-grain weight. Under the cultivation mode of pothole seedling transplanting and carpet seedling transplanting, compared with CK, the two-year yield of 40+80 and 40+100 controlled-release fertilizer treatments were higher than CK, and the two-year yield of 40+100 controlled-release fertilizer treatments was the highest, which was significantly increased by 7.3% and 9.2%, respectively. The reason was that 40+100 controlled-release fertilizer treatment had higher effective panicle number and population glume amount. Compared with 40+80 and 40+120 controlled-release fertilizer treatments, the nutrient absorption law of 40+100 controlled-release fertilizer treatment was more consistent with Nanjing 9108, which not only ensured the occurrence of early tillering, but also ensured the stable production of photosynthetic substances at later stage, thus obtaining stable panicle number, grains per panicle, and 1000-grain weight. Compared with CK, the nitrogen recovery efficiency, nitrogen agronomic efficiency, nitrogen physiological efficiency, and nitrogen partial productivity of 40+100 controlled-release fertilizer treatments were significantly increased by 10.0%-12.5%, 24.6%-30.5%, 11.4%-18.6%, and 7.3%-9.1%, respectively. In conclusion, the mechanical transplanting with pothole seedlings (MT) had obvious advantages over mechanical transplanting with carpet seedlings (MC), which was a cultivation method that was conducive to high-quality <italic>japonica</italic> rice. At the same time, the 40+100 controlled-release fertilizer ratio could better meet the nutrient requirements of good-quality <italic>japonica</italic> rice at various stages, and could obtain high yield, which could be used as a simplified fertilization scheme for high-quality <italic>japonica</italic> rice.

Effects of different agricultural treatments on narrowing winter wheat yield gap and nitrogen use efficiency in China

Under the limited cultivated land area and the pursuit of sustainable agricultural development, it is essential for the safety of grain production to study agricultural management approaches on narrowing the winter wheat yield gap and improving nitrogen use efficiency (NUE) in China. In this study, DSSAT-CERES-Wheat Model is used to simulate winter wheat yield under different agricultural treatments, and we analyze yield gaps and NUE with different management scenarios at regional scales and evaluate the suitable approaches for reducing yield gap and increasing NUE. The results show that, the potential of narrowing yield gap ranges 300–900 kg ha–1 with soil nutrients increase, 400–1 200 kg ha–1 with sowing date adjustment and 0–400 kg ha–1 with planting density increase as well as 700–2 200 kg ha–1 with adding nitrogen fertilizer. Contribution rates of management measures of soil nutrients, sowing date adjusting, planting density, and nitrogen fertilizers are 5–15%, 5–15%, 0–4%, and 10–20%, respectively. Difference in nitrogen partial productivity ranges 3–10 kg kg–1 for soil nutrients, 1–10 kg kg–1 for sowing date adjusting, 1–5 kg kg–1 for planting density increase, and –12–0 kg kg–1 for adding nitrogen fertilizers, respectively. It indicates that four treatments can narrow yield gap and improve the NUE in varying degrees, but increasing nitrogen fertilizer leads to the decrease of NUE.

Nitrogen Effects on Yield, Quality and Physiological Characteristics of Giant Rice

In China, the quantity of nitrogen fertilizer applied is large, but as a consequence of a high level of loss, its utilization rate is low. Compared to common rice, the new giant rice has interesting characteristics, namely high biological yield and good efficient use of fertilizer. However, it becomes urgent to further consider the appropriate rate of nitrogen fertilizer to be applied. The giant rice varieties Feng5 and Feng6 were set up in a pot experiment and a field experiment under five doses of nitrogen fertilizers, namely, 0 kg·ha−1 (CK), 75 kg·ha−1 (T1), 150 kg·ha−1 (T2), 225 kg·ha−1 (T3) and 300 kg·ha−1 (T4). Parameters such as leaf area index (LAI), lodging index (LI), nitrogen utilization rate, photosynthesis rate and grain yield were measured. The results showed that with the increase of nitrogen dose in a certain range, LAI, plant height, the number of tillers, net photosynthetic rate (NPn), the transpiration rate (Tr), and the grain yield increased while the lodging index (LI), the nitrogen agronomic utilization rate (AE) and nitrogen partial productivity (PFPN) decreased. Additionally, with the increase of nitrogen application, the grain yield index (HI) and nitrogen contribution rate (FCRN) of rice presented a parabolic trend.

Coupling effects of periodic rewatering after drought stress and nitrogen fertilizer on growth and water and nitrogen productivity of Coffea arabica

The effects of periodic rewatering after drought stress and nitrogen fertilizer on growth, yield, photosynthetic characteristics of leaves and water and nitrogen productivity of Coffea arabica (Katim P7963) were studied under different nitrogen application levels in 2.5 consecutive years. Irrigation (periodic rewatering after drought stress) and nitrogen were designed as two factors, with four modes of irrigation, namely, full irrigation (IF-F: 100%ET0+100%ET0, ET0 was reference crop evapotranspiration), rewatering after light drought stress (IL-F: 80%ET0+100%ET0), rewatering after moderate drought stress (IM-F: 60%ET0+100%ET0) and rewatering after severe drought stress (IS-F: 40%ET0+100%ET0), and three levels of nitrogen, namely, high nitrogen (NH: 750 kg N·hm-2 each time), middle nitrogen (NM: 500 kg N·hm-2 each time), low nitrogen (NL: 250 kg N·hm-2 each time), and nitrogen was equally applied for 4 times. The results showed that irrigation and nitrogen had significant effect on plant height, stem diameter, yield and water and nitrogen productivity of C. arabica, and plant height and stem diameter showed S-curve with the day ordinal number, and leaf photosynthesis decreased significantly under drought stress but most photosynthesis index recovered somewhat after rewatering. Compared with IF-F, IL-F increased dry bean yield by 6.9%, while IM-F and IS-F decreased dry bean yield by 15.2% and 38.5%, respectively; IL-F and IM-F increased water use efficiency by 18.8% and 6.0%, respectively, while IS-F decreased water use efficiency by 12.1%; IL-F increased nitrogen partial productivity by 6.1%, while IM-F and IS-F decreased nitrogen partial productivity by 14.0% and 36.0%, respectively. Compared with NH, NM increased dry bean yield and water use efficiency by 20.9% and 19.3%, while NL decreased dry bean yield and water use efficiency by 42.4% and 41.9%, respectively; NM and NL increased nitrogen partial productivity by 81.4% and 72.9%, respectively. Compared with IF-FNH, IL-FNM increased dry bean yield, water use efficiency and nitrogen partial productivity by 37.6%, 52.9% and 106.4%, respectively. Regression analysis showed that the yield of dry bean was the maximum (2362 kg·hm-2) when the irrigation amount was 318 mm and the nitrogen application amount was 583 kg·hm-2; the water use efficiency was the maximum (0.78 kg·m-3) when the irrigationamount was 295 mm and the nitrogen application amount was 584 kg·hm-2, that's to say when yield of dry bean and water use efficiency reach the maximum value at the same time, the combination was the closest to IL-FNM. Therefore, the best combination of water and nitrogen model for C. arabica was IL-FNM.

Responses of dry matter, nitrogen accumulation and distribution and nitrogen utilization of pepper to new-type fertilizers in Guizhou yellow soil.

In order to explore the pepper yield responses to new-type fertilizers in yellow soil in Guizhou Province, a pot experiment, with the variety of "Bola 5", was conducted to estimate the effects of four new-type fertilizers, including water retaining fertilizer (BSX), stable slow release fertilizer (WDX), coated slow release fertilizer (BMX) and long-lasting nitrogen fertilizer (CXDF), on the accumulation and distribution of dry matter and nitrogen (N) uptake and N use efficiency. The results showed that the application of new-type fertilizers could significantly influence the accumulation and distribution of dry matter and shoot N uptake. Compared with dry matter accumulation, the start time and the end time of N accumulation during fast-growing period were advanced by 17-26 d and 28-45 d, respectively, and the duration of N accumulation in fast-growing period was shorter by 7-23 d, which indicated that the occurrence time of N accumulation was prior to the accumulation of dry matter. In contrast to the common compound fertilizer (FHF) treatment, the occurrence time of dry matter and nitrogen accumulation in the treatments with new-type fertili-zers (BSX, WDX, BMX and CXDF) were obviously lagged, and the lag time was longest in the BMX treatment. However, it had a shorter duration of fast-growing stage and a maximum accumulation rate for the WDX treatment, revealing that WDX could realize the high nutrient use efficiency in a short time. The post-anthesis dry matter and N accumulation accounted for 63.0%, 20.1% and 73.3%, 20.5% for the BSX and BMX treatments, respectively, while these proportions for the WDX were 59.3% and 11.6%, respectively. This indicated that BSX and BMX were beneficial to promote dry matter and N assimilation after flowering, while WDX was conducive to dry matter and nutrients accumulation before flowering. Compared with the FHF treatment, new-type fertilizers (BSX, WDX and BMX) application could significantly improve N use efficiency. Nitrogen partial productivity, nitrogen agronomic efficiency and nitrogen apparent utilization rate of the WDX treatment were the highest, with the average of 66.74 kg·kg-1, 44.28 kg·kg-1 and 54.7%, respectively. Consequently, these four new-type fertilizers were sui-table for pepper cultivation in Guizhou, in which the yield response to the WDX was the best.