Nitrogen Fertilizer Application Rates Research Articles

Slow-Release Nitrogen Fertilizer Promotes the Bacterial Diversity to Drive Soil Multifunctionality

The application of slow-release nitrogen fertilizer not only economizes labor input, but also decreases the frequency of use of mechanical intakes, with significant implications in advancing modern intensive agricultural production. Whether slow-release nitrogen fertilizer application can influence the association between microbial diversity and soil multifunctionality remains controversial. This study analyzed the spatial variances of soil environmental factors, soil multifunctionality, and their correlations with bacterial and fungal communities under five nitrogen application rates. The key factors influencing the dominant microbial species and community structures at different spatial locations were determined by the slow-release nitrogen fertilizer application rate, and the driving factors and dominant species of soil multifunctionality were identified. In contrast to the control group, moderate slow-release nitrogen fertilizer application enhanced soil multifunctionality and ameliorated the resilience of microbial diversity loss at diverse spatial locations resulting from irrational nitrogen fertilizer application. The resilience of the fungal community to disturbances caused by fertilization was lower than that of the bacterial community. Bacterial diversity exhibited a significant correlation with soil multifunctionality, and the soil multifunctionality intensity under 240 kg ha−1 treatment increased by 159.01% compared to the CK. The main dominant bacterial communities and the dominant fungal community Ascomycota affected soil multifunctionality through slow-release nitrogen fertilizer application. Structural equation modeling and random forest analysis demonstrated that bacterial community diversity, particularly in bulk soil and the rhizosphere, community composition, and soil nitrogen form are the primary driving factors of soil multifunctionality. Results indicated that the microbial niche alterations induced by slow-release nitrogen fertilizer application positively affect soil multifunctionality.

Optimizing Irrigation and Nitrogen Levels for Enhanced Cabbage Growth in Yobe's Semi-Arid Region

This study investigated the effects of irrigation schedules and nitrogen fertilizer application rates on the growth and productivity of cabbage in Damaturu, Yobe State. Using a Randomized Complete Block Design (RCBD) in a 3x5 factorial arrangement with three replications, we tested three irrigation intervals “3, 6, and 9 days” and five nitrogen fertilizer levels “0, 25, 50, 75, and 100 kg ha⁻¹” on an improved cabbage variety (Datdiku-5m). Results indicated cabbage growth positively responded to optimal irrigation intervals and increasing nitrogen fertilizer rates. The combination of 6-day irrigation intervals and 100 kg ha⁻¹ of nitrogen fertilizer resulted in impressive outcomes: a tallest head height of 18.92 cm, the largest head diameter of 16.95 cm, maximum plant height of 24.92 cm, the largest plant spread of 37.12 cm, a maximum marketable yield of 63.5 t/ha, and the highest total yield of 71.52 t/ha (Table 3). This combination ensures an adequate supply of water and nutrients, promoting robust growth and significant yield in semi-arid region. In contrast, lower irrigation intervals (9 days) and reduced nitrogen levels (0-50 kg ha⁻¹) led to stunted growth and lower productivity metrics, illustrating the critical role of proper water and nutrient management in achieving optimal cabbage yields. Therefore, adopting a 6-day irrigation schedule and applying 100 kg ha⁻¹ of nitrogen fertilizer may effectively increase cabbage yield. Future research should explore different nitrogen fertilizer rates and the combined effects of various nutrients with different irrigation intervals to further assess their impact.

Response of Yield of Shallot (<i>Allium ascalonium</i> L.) to Nitrogen Fertilizer Rates and Spacing Under Irrigation at Mulo, Ethiopia

The shallot (<i>Allium ascalonium</i> L.) is one of the important alliaceous crops cultivated in many tropical countries. It is an important horticultural crop used to flavor the local stew "wot" and a source of income for farmers in Ethiopia. However, the productivity of shallot is low at study area due to various limiting factors such as low soil fertility, plant population and lack of improved agronomic practices. A field experiment was conducted to investigate the effect of intra-row spacing and nitrogen fertilizer levels on growth, yield and quality of shallot at Mulo District, Oromia Regional state, Ethiopia during 2021/22 off season. The treatments consisted of four intra-row spacing (5, 10, 15 and 20) cm and four levels of nitrogen fertilizer (0, 50, 100 and 150) kgNha<sup>-1</sup> tested in a randomized complete block design with three replications. Data on shallot yield was collected. The interaction effect of intra-row spacing and nitrogen fertilizer influenced the marketable yield, unmarketable yield, bulb weight, bulb fresh weight, bulb dry weight, dry matter and total yield. As a result, the treatment combination of 150kgha<sup>-1</sup> nitrogen and 15cm intra-row spacing yielded the highest net benefit of shallot (Eth-Birr 1,012,274), followed by the treatment combination of 150kgha<sup>-1</sup> nitrogen and 20 cm intra-row spacing. In conclusion, the above findings indicated that the combined application of 150kgNha<sup>-1</sup> with 15 cm spacing can improve shallot growth and productivity in the Mulo district area. However, more research needs to be done in different seasons and locations, taking into account the application rate of nitrogen fertilizer and different intra-row spacing, to generate more reliable information.

Improvement of Transplanting Rice Yield and Nitrogen Use Efficiency by Increasing Planting Density in Northeast China Under the Optimal Nitrogen Split-Fertilizer Applications

There are few studies on how nitrogen (N) fertilizer application rates and transplanting densities impact rice yield, root distribution, and N use efficiency in the cold regions of Northeast China. This research involved a two-year field trial utilizing Jinongda 667 as the material. In 2021, three N split-fertilizer applications—T1 (6:3:1), T2 (5:3:2), T3 (4:3:3)—and two transplanting densities—D1 (30 cm × 13.3 cm) and D2 (30 cm × 20 cm)—were compared with the conventional cultivation mode (T0: 175 kg N hm−2, 6:3:1), whereby the N application mode most suitable for increasing density was explored. In 2022, four N application levels—0 (N0), 125 (N1), 150 (N2), and 175 (N3) kg N hm−2—were assessed under the same density treatment to analyze the yield, resource utilization efficiency, and root traits of Jinongda 667. The results indicated that when the transplanting density was 30 cm × 13.3 cm, the application of 5:3:2 fertilizer was more conducive to improving rice yield. Increasing planting density under reduced N input significantly enhanced both rice yield and N use efficiency. In contrast to the conventional cultivation method (D2N3), the treatment of increased planting density (D1N2) under reduced N input led to a 21.2% rise in the number of panicles per square meter and an 8.6% boost in rice yield. Furthermore, increasing planting density under reduced N input significantly enhanced the agronomic efficiency of N fertilizer, the apparent utilization rate, and the N harvest index. It also boosted the SPAD value, photosynthetic rate, and the utilization efficiency of light and N resources in rice. However, it was noted that root enzyme activity decreased. This study demonstrated that increasing planting density, combined with the N application mode of 5:3:2 and an N application rate of 150 kg hm−2, maximized resource utilization efficiency, optimized root absorption capacity, and resulted in higher yields.

Effects of Different Straw Returning Periods and Nitrogen Fertilizer Combinations on Rice Roots and Yield in Saline–Sodic Soil

Straw return is an effective management practice for improving physical and chemical properties of saline–sodic soil in Northeast China. Straw decomposition and nutrient release are deeply influenced by soil and climatic factors. In Northeast China, straw decomposes slowly due to the long winter with low temperatures. Therefore, the season of straw return may be a key issue affecting rice. However, the impact of returning straw in different seasons on rice is disregarded and not commonly researched. We conducted a 2-year field experiment, including two residue management treatments: spring straw return treatment (SR) and autumn straw return treatment (AR), each containing five different N rates (0, 90, 180, 270, and 360 kg ha−1) as sub-treatments. The results reveal that, compared with the spring straw returning treatment, the autumn straw returning treatment significantly improved root morphology and root vigor and increased the number of spikes per unit area, which directly increased rice yield by 4.76% (2020) and 6.62% (2021). In addition, rice yield showed an increasing and then decreasing trend with the increase in N fertilizer application, and it was at its maximum when the N application rate was 270 kg ha−1. Compared to the spring straw return treatment, the autumn straw return treatment was able to reduce 31.46% (2020) and 38.48% (2021) of N fertilizer application without decreasing rice yield. Our findings demonstrate that straw return combined with nitrogen fertilization may be a promising management practice for improving rice root systems and yield in saline–sodic soils, and under the conditions of the autumn straw returning treatment, the best nitrogen fertilizer application rate was 270 kg ha−1.

Combination of nitrogen and organic fertilizers reduce N2O emissions while increasing winter wheat grain yields and quality in China

Wheat grain yields, quality, and nitrous oxide (N2O) emissions were controlled through the type and application rate of nitrogen (N) fertilizer. Here, we investigated the optimal management of N fertilization by examining the combined effects of organic and N fertilizers on wheat yields, quality, and N2O emissions. Field trials under six treatments were located on campus farms at Anhui Science and Technology University, including farmer’s common practice (270 kg N ha-1, N270), 2/3 reduction in N270 (90 kg N ha-1, N90), organic fertilizer with equal N270 (OF270), 2/3 reduction in OF270 (OF90), 4/5 reduction OF270 + 1/5 reduction N270 (20% OF270 + 80% N270), and 4/5 reduction OF90 + 1/5 reduction N90 (20% OF90 + 80% N90) were applied to winter wheat. The plots were arranged in a randomized complete block experimental design. The N2O emissions were quantified under different fertilization measures in the peak wheat growing season during sowing, jointing, and grain filling stages, respectively. Compared with N270 and N90 treatments, N2O emissions were significantly decreased by 18.6% and 27.2%, respectively, under 20% OF270 + 80% N270% and 20% OF90 + 80% N90 (p < 0.05). Further, N2O emissions in N270 were increased by 50.8% relative to N90. Wheat yields increased significantly under 20% OF90 + 80% N90 by 27.6% (N270) and 16.4% (N90), and were considerably enhanced under 20% OF270 + 80% N270 by 40.6% (N270) and 12.7% (N90) in contrast to OF270 and N270 (p < 0.05). Compared with N90, the content of wet gluten, protein and starch under 20% OF90 + 80% N90 treatment significantly increased by 7.7%, 13.8% and 7.9%, and enhanced by 7.6%, 4.8%, 8.0% relative to OF90, respectively (p < 0.05). The starch content increased significantly by 2.0%, whereas the settlement value decreased considerably by 2.9% under 20% OF270 + 80% N270 (p < 0.05), and there was no notable difference in the wet gluten and protein contents (p > 0.05). Our findings indicated that organic fertilizer mixed with N fertilizer can effectively reduce N2O emissions, increase both the grain yields and quality in wheat field compared with N fertilizer alone.

Effect of Irrigation Depth and Nitrogen Fertilizer Rates on Pepper (Capsicum annum L.) Yield and Water Use Efficiency in Tselemty District, Tigray, Ethiopia

Optimizing agricultural crop production involves utilizing proper irrigation and fertilization techniques. A two-year experiment conducted in the Tselemty district during the off seasons of 2019 and 2020 aimed to assess the impact of varying irrigation levels and nitrogen fertilizer application rates on the growth, yield, and crop water productivity of pepper. The study included three irrigation levels (75%, 100%, and 125% of the required irrigation) and three nitrogen fertilizer application rates (75%, 100%, and 125% of the recommended amount). Analysis of the results using Gen-Stat software revealed that most pepper yield attributes were not significantly affected by the different irrigation and fertilizer levels. However, the marketable yield showed significant variation based on the combined application rates. The research indicates that, under ideal circumstances, the optimal approach for pepper growers is a combination of meeting 100% of the irrigation requirement and applying 100% of the recommended nitrogen fertilizer rate. Nevertheless, in scenarios where water resources are limited and fertilizer expenses are high, a reduced irrigation level of 75% of the requirement coupled with 75% of the recommended nitrogen fertilizer rate could be a viable alternative that does not lead to a substantial decrease in yield.

Quantitative assessment of the effects of rising temperature on the grain protein of winter wheat in china and its adaptive strategies

With advancements in genetics and technology, wheat yields have continuously increased, but grain quality has remained stagnant or even decreased in recent decades. The effects of temperature on the future grain quality of winter wheat in China are unknown. This study used an improved WheatGrow model, along with two future temperature scenarios, to quantify the regional impacts of temperature increases on grain protein in China and aimed to find effective strategies to adapt to the impact of temperature increases on quality. Compared with those in the baseline period, the protein concentration of wheat grains in the main winter wheat production region of China increased by 0.27% and 0.41% under the 1.5 ℃ and 2.0 ℃ temperature increase scenarios, respectively. However, the grain protein concentrations in the Sichuan Basin of Medium and Weak Gluten Wheat Subregion (Ⅴ) decreased. The temperature rise was estimated to increase the proportion of strong gluten-type wheat but reduce the proportion of medium gluten-type wheat, with the proportion of weak gluten-type wheat changing slightly. Advanced planting date was projected to increase the grain protein concentration in the Northern Strong Gluten Wheat Subregion (Ⅰ), the Northern of Huang-Huai Strong and Medium Gluten Wheat Subregion (Ⅱ), the Southern of Huang-Huai Medium Gluten Wheat Subregion (Ⅲ) and the Yangzi River of Medium and Weak Gluten Wheat Subregion (Ⅳ), whereas a delayed planting date reduced the protein concentration in subregions Ⅰ, Ⅱ, and Ⅲ. In addition, the grain protein concentration was not significantly affected in the higher high-temperature threshold varieties in the southern winter wheat production region under the global warming scenarios. However, if more strong gluten-type wheat is required in the northern China in the future, varieties with lower high-temperature thresholds can be selected without considering wheat yields. Moreover, increasing the nitrogen fertilizer application rate could further increase the wheat protein concentration under future warming scenarios, and the protein concentration of wheat was more sensitive to the nitrogen fertilizer application rate in the northern winter wheat production region than in the southern region. These findings are crucial for improving grain quality across different wheat production regions of China in the future.

Nitrogen fertiliser application rate to temperate mid-season grass: Digestion, nitrogen balance and rumen microbiota in beef cattle, and rumen fermentation and methane production in vitro

Nitrogen (N) excretion by cattle, particularly urinary N, can have detrimental environmental impacts on air and water quality, and contributes to greenhouse gas emissions. The effects of increasing the application rate of inorganic N fertiliser from 15 (N15) to 80 (N80) kg/ha per cut to Lolium perenne dominant swards in summer, on intake, rumen fermentation, rumen microbial populations, apparent total-tract digestibility and N-balance in beef cattle, and in vitro fermentation and methane output, were studied. Sixteen suckler-bred Charolais steers, used in a randomised block design experiment, were offered fresh grass mechanically harvested 21-d after N fertiliser application. Similar grass was incubated in an eight-vessel in vitro RUSITEC system. Grass crude protein concentration was 50 g/kg dry matter (DM) higher for N80 compared to N15. There was no difference in grass DM intake between treatments. Rumen fermentation variables did not differ between treatments, except for the molar proportion of propionate, which was greater for N80 than N15. Gross microbial community structure in the rumen was not significantly altered by inorganic N fertiliser application rate. The relative abundance of individual genera Lachnospiraceae_NK3A320_group and Ruminococcaceae_NK4A214_group, and Acetitomaculum were significantly lower at the higher N application rate. Mean plasma urea concentration was greater for N80 compared to N15. In vivo digestibility of DM, organic matter, neutral detergent fibre and acid detergent fibre was unaffected by fertiliser N application rate. Nitrogen intake was 75 g/d greater, and urinary and faecal N excretion were 20 and 5 g/d greater, respectively, for N80 than N15. The quantity of N retained and N use efficiency was greater for N80 compared to N15. In vitro NH3 concentration was greater for N80 than N15, whereas other rumen fermentation variables, and in vitro methane and total gas output, did not differ between treatments. Reducing the inorganic N fertiliser rate applied to mid-season temperate grass reduced N excretion from beef cattle, which is environmentally beneficial, with no effect on in vitro methane production.

Long-term integrated agronomic optimization maximizes soil quality and synergistically improves wheat yield and nitrogen use efficiency

Integrated agronomic optimization (IAO) adopts suitable crop varieties, sowing dates, planting density and advanced nutrient management to redesign the entire production system according to the local environment, which can achieve synergistic improvements in crop yields and resource utilization. However, the intensity and magnitude of the impacts of IAO on soil quality under long-term intensive production and high nitrogen use efficiency (NUE) require further clarification. Based on a 13-year field experiment conducted in Dawenkou, Tai'an, China, we investigated the effects of four cultivation modes on the grain yield, NUE, soil aggregate structure, as well as the fraction of organic matter (SOM) and soil quality, reflected by integrated fertility index (IFI) during the winter wheat maturation period in 2020–2022. The four cultivation modes were traditional local farming (T1), farmer-based improvement (T2), increased yield regardless of production cost (T3), and integrated soil–crop system management (T4). As IAO modes, T2 and T4 were characterized by denser planting, reduced nitrogen (N) fertilizer application rates, and delayed sowing compared to T1 and T3, respectively. In this long-term experiment, IAO was found to maintain aggregate stability, increase SOM content (by increasing organic carbon and total nitrogen of the light fraction (LF) and the particulate organic matter fraction (POM)), and improve SOM quality by increasing the proportions of LF and POM and the ratio of organic carbon to total nitrogen in SOM. Compared to T1, the IFI of T2, T3, and T4 increased by 10.91, 23.38, 25.55%, and by 17.78, 6.41, 28.94% in the 0–20 and 20–40 cm soil layers, respectively. The grain yield of T4 was 22.52% higher than that of T1, reaching 95.98% of that in T3. Furthermore, NUE of T4 was 35.61% higher than that of T1 and T3. In conclusion, our results suggest that T4 synergistically increases grain yield and NUE in winter wheat, while maximizing soil quality.

Effects of Straw and Fertilizer Managements on Nitrogen Loss in Rice Cultivation in Taihu Lake Basin

Nitrogen loss from rice systems is an important source of agricultural non-point source pollution. Many studies revolve around reducing the rate of nitrogen fertilizer application. However, studies examining the characteristics of nitrogen loss in multiple loss paths （runoff, leaching, and lateral seepage） under different straw and fertilizer managements are lacking. Therefore, a study was carried out based on a rice field planted for more than 20 years with straw continuously returned to the field for more than 5 years in Taihu lake basin. The effects of straw and fertilizer managements on nitrogen loss in different paths during the whole growth period of rice were studied. Moreover, straw and fertilizer managements were evaluated by their production suitability and environmental friendliness based on crop yield, nitrogen use efficiency, and nitrogen loss. The results showed that straw removal from the field increased the response sensitivity of nitrogen accumulation in plant tissue to nitrogen application. The nitrogen loss in the rice season was 9-17 kg·hm-2, accounting for 5%-7% of the nitrogen application rate. Straw removal increased the risk of nitrogen loss when soaking water discharged. Straw returning could decrease the nitrogen loss by more than 15%, though the effect of straw on nitrogen loss via lateral seepage was not clear. Furthermore, the suitable substitution of organic fertilizer （30% in this study） could respectively reduce the amount of nitrogen loss via runoff, leaching, and lateral seepage by 16%, 26%, and 37% compared with the fertilizer application under the same nitrogen gradient. In conclusion, the implementation of straw returning and fertilizer type optimization measures effectively reduced the nitrogen loss for unit weight of rice production and realized the balance between agricultural production and environmental protection.

Effect of nitrogen fertilizer on the quality traits of Indica rice with different amylose contents.

Nitrogen is a key factor affecting the quality of rice. Studying the impact of nitrogen fertilizer on the taste, physicochemical properties, and starch structure of Indica rice with different amylose contents is of great significance for scientifically fertilizing and cultivating high-quality rice varieties for consumption. The results indicate that increasing nitrogen fertilizer application reduces the amylose content and increases the protein content, resulting in a decrease in taste quality. Simultaneously, it reduces the intergranular porosity of starch particles, improving the appearance and milling quality of rice. Compared to the N1 treatment (nitrogen fertilizer application rate of 90 kg ha-1), the taste of low-amylose rice (Yixiangyou 2115) and high-amylose rice (Byou 268) decreased by 14.24% and 19.79%, respectively, under N4 treatment (nitrogen fertilizer application rate of 270 kg ha-1). The effect of nitrogen fertilizer on low-amylose rice is mainly reflected in increased rice hardness, enthalpy value, and setback viscosity, resulting in a decline in taste. The effect of nitrogen fertilizer on high-amylose rice is mainly reflected in a decrease in peak viscosity, an increase in gelatinization temperature, and crystallinity under high nitrogen levels. Increasing nitrogen fertilizer application can improve the appearance and milling quality of rice, but it also leads to an increase in protein content, hardness, gelatinization enthalpy, decrease in breakdown value, and a decline in palatability. In practical production, different production measures should be taken according to different production goals. © 2024 Society of Chemical Industry.

Optimal Nitrogen Fertilizer Rates for Soybean Cultivation

The soybean (Glycine max. L. Merr) can satisfy a large portion of its requirement for nitrogen (N) by living in symbiosis with symbiotic bacteria. However, this source of N may be inadequate in varieties with high yield potential. To fully exploit this potential, soybeans should additionally utilize mineral forms of nitrogen present in the soil. The aim of this study was to determine the effect of varied nitrogen fertilizer application rates on the dry weight of the separated parts of soybean plants and the whole plant, including the number and weight of root nodules, the potential to reduce atmospheric nitrogen (N2), and the content and uptake of nitrogen. Four levels of pre-sowing nitrogen fertilizer supply were tested: 0, 60, 120, and 180 kg N·ha−1. Measurements of the tested parameters were taken during the flowering stage and the fully ripe stage. During the flowering stage, a reduction in the number of root nodules was observed following the application of 120 and 180 kg N·ha−1. In the fully ripe stage, each increase in nitrogen application caused a systematic decrease in the number of nodules on the roots. Increasing the level of nitrogen application therefore reduced the N2 fixation potential of soybeans, regardless of the developmental stage. The use of high doses of nitrogen in soybean cultivation did not increase seed yield or the weight of the entire plant. With high doses of nitrogen, the content and accumulation of nitrogen in soybean seeds and total mass did not increase. Therefore, the content and yield of crude protein did not increase. The main organ of nitrogen accumulation in the soybean flowering stage was the leaves (58.6–64.8% of total N uptake), however, in the fully ripe stage, it was the seeds (66.8–74.2% of total N uptake).

Effects of nitrogen fertilization on the fate of high-risk antibiotic resistance genes in reclaimed water-irrigated soil and plants

High-risk antibiotic resistance genes (ARGs) in reclaimed water-irrigated soil pose a potential threat to ecosystem and human health. Inorganic fertilization – including with nitrogen, a key ingredient in agricultural production – may affect the ARG profile in soil. However, little is known about nitrogen fertilization's influence on ARGs profiles in the soil–plant system. This study investigated the effects of different nitrogen fertilizer types (CO(NH2)2, NO3–-N (NaNO3) and NH4+-N (NH4HCO3)) and different nitrogen fertilizer application rates (low, medium, high) on the distribution of high-risk ARGs in reclaimed water-irrigated soil and plants using quantitative PCR, high-throughput sequencing and metagenomic sequencing. Soil microcosms results revealed that nitrogen fertilization significantly affected the pattern of high-risk ARGs in soil, and also affected high-risk ARGs abundance and transfer capacity in plants. Compared with nitrogen fertilizer application rate, nitrogen fertilizer types significantly contributed to enhancing the soil resistome, with the order of CO(NH2)2 > NO3–-N ≈ NH4+-N. The medium application of NO3–-N and NH4+-N significantly reduced high-risk ARGs abundance in the leaf endophyte. Bacterial community mainly drove the variation of ARGs in nitrogen-fertilized soil–plant system, and class I integron and metal resistance genes (MRGs) also had direct effects on these high-risk ARGs. A similar high-risk ARGs pattern was also found in field plot experiments, and several dangerous pathogens were observed as the main high-risk ARGs potential hosts in nitrogen-fertilized soil. Based on an economic assessment, application of NH4+-N (NH4HCO3) could reduce costs by $1,312.83 ha−1 compared with NO3–-N (NaNO3). These results showed that the more important role of nitrogen type might be an effective and economical way to control high-risk ARGs spread in soil–plant system under reclaimed water irrigation.

Rate and time of nitrogen fertilizer application for winter camelina

AbstractWinter camelina [Camelina sativa (L.) Crantz] is a potential third crop to diversify maize (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotations in the upper Midwest. Although generally considered a low‐input crop, empirical evidence suggests that it responds to added nitrogen (N) fertilization. However, optimum agronomic N rates have not been extensively studied in the region. A study was conducted from fall 2018 to fall 2020 at three locations to assess the effects of N fertilizer application time (all N‐rate applied in spring and N‐rate split applied in fall and spring) and rates on biomass and seed yield, and quality of winter camelina. Nitrogen application time did not affect yields. Both biomass and seed yields were greatly affected by N rates at all locations. Nitrogen had minimal effects on the oil and protein content of seeds, although greater N rates were associated with a slight decrease in oil content and a slight increase in protein content. The number of branches and silicles per plant varied significantly with N rates in all locations. The seed‐to‐silicle ratio showed significant differences in two out of three locations. Residual soil N increased with increasing N rates. A fertilization rate of 67 kg ha−1 provided the highest camelina seed yield. While this study has determined the agronomic maximum rate for applied N, further economic analysis could provide comprehensive decision‐making for farmers.

Prediction Model of Nitrogen, Phosphorus, and Potassium Fertilizer Application Rate for Greenhouse Tomatoes under Different Soil Fertility Conditions

To reach the target yield of crops, nutrient management is essential. Selecting the appropriate prediction model and adjusting the nutrient supply based on the actual situation can effectively improve the nutrient utilization efficiency, crop yield, and product quality. Therefore, a prediction model of the NPK fertilizer application rate for greenhouse tomatoes under the target yield was studied in this study. Under low, medium, and high soil fertility conditions, a neural network prediction model based on the sparrow search algorithm (SSA-NN), a neural network prediction model based on the improved sparrow search algorithm (ISSA-NN), and a neural network prediction model based on the hybrid algorithm (HA-NN) were used to predict the NPK fertilizer application rate for greenhouse tomatoes. The experimental results indicated that the evaluation indexes (i.e., the mean square error (MSE), explained variance score (EVS), and coefficient of determination (R2)) of the HA-NN prediction model proposed in this study were superior than the SSA-NN and ISSA-NN prediction models under three different soil fertility conditions. Under high soil fertility, compared with the SSA-NN prediction model, the MSE of the ISSA-NN and HA-NN prediction models decreased to 0.007 and 0.005, respectively; the EVS increased to 0.871 and 0.908, respectively; and the R2 increased to 0.862 and 0.899, respectively. This study showed that the HA–NN prediction model was superior in predicting the NPK fertilizer application rate for greenhouse tomatoes under three different soil fertility conditions. Due to the significance of NPK fertilizer application rate prediction for greenhouse tomatoes, this technique is expected to bring benefits to agricultural production management and decision support.

Agronomic performance of maize of contrasting maturities at varying rates of nitrogen fertilizer application in a tropical rainforest agroecology

Agronomic performance of maize of contrasting maturities at varying rates of nitrogen fertilizer application in a tropical rainforest agroecology

Rock Phosphate and Biochar Effects on Greenhouse Gas Emissions and Soil Fertility in Southern Alberta Potato Field

The application of biochar soil amendment and rock phosphate fertilizer to the soil could lead to achieving net zero emissions and food security; however, the effectiveness of using biochar and rock phosphate in southern Alberta brown chernozemic soil is not yet assessed. In the first trial of this study, varying levels of urea (N), with varying levels of biochar (B) were applied. The same level of rock phosphate (RP) and triple super phosphate (TSP) were applied to compare efficiency of the two fertilizers. The second trial involved applying the same nutrients, but with higher levels than the first trial. The results indicated that the fertilizer application rates did not affect the growth and yield of potatoes because of the application rates of the fertilizer and fertility status of the soil, whereas in the second trial, TSP and RP treatments had the same growth and yield. Furthermore, the high application rate of nitrogen fertilizer and RP with or without biochar in the potato plot emitted high nitrous oxide gas emissions while the low application rate of nitrogen fertilizer and RP kept the carbon dioxide in the soil. Nevertheless, in the second experiment, the application of biochar and rock phosphate reduced nitrous oxide and carbon dioxide emissions. We observed high residual nitrogen and manganese nutrients after harvest in the plot treated to rock phosphate and biochar. Therefore, rock phosphate and biochar have the potential to increase food production and mitigate climate change.

Enhancing root physiology for increased yield in water-saving and drought-resistance rice with optimal irrigation and nitrogen.

Water-saving and drought-resistance rice (WDR) plays a vital role in the sustainable development of agriculture. Nevertheless, the impacts and processes of water and nitrogen on grain yield in WDR remain unclear. In this study, Hanyou 73 (WDR) and Hyou 518 (rice) were used as materials. Three kinds of nitrogen fertilizer application rate (NFAR) were set in the pot experiment, including no NFAR (nitrogen as urea applied at 0 g/pot), medium NFAR (nitrogen as urea applied at 15.6 g/pot), and high NFAR (nitrogen as urea applied at 31.2 g/pot). Two irrigation regimes, continuous flooding cultivation and water stress, were set under each NFAR. The relationships between root and shoot morphophysiology and grain yield in WDR were explored. The results demonstrated the following: 1) under the same irrigation regime, the grain yield of two varieties increased with the increase of NFAR. Under the same NFAR, the reduction of irrigation amount significantly reduced the grain yield in Hyou 518 (7.1%-15.1%) but had no substantial influence on the grain yield in Hanyou 73. 2) Under the same irrigation regime, increasing the NFAR could improve the root morphophysiology (root dry weight, root oxidation activity, root bleeding rate, root total absorbing surface area, root active absorbing surface area, and zeatin + zeatin riboside contents in roots) and aboveground physiological indexes (leaf photosynthetic rate, non-structural carbohydrate accumulation in stems, and nitrate reductase activity in leaves) in two varieties. Under the same NFAR, increasing the irrigation amount could significantly increase the above indexes in Hyou 518 (except root dry weight) but has little effect on Hanyou 73. 3) Analysis of correlations revealed that the grain yield of Hyou 518 and Hanyou 73 was basically positively correlated with aboveground physiology and root morphophysiology, respectively. The grain yield could be maintained by water stress under medium NFAR in WDR. The improvement of root morphophysiology is a major factor for high yield under the irrigation regime and NFAR treatments in WDR.

Regulation of photoassimilate transportation and nitrogen uptake to decrease greenhouse gas emissions in ratooning rice with higher economic return by optimized nitrogen supplies

Mechanized harvesting of the main crop rice, with low stubble height in rice ratooning is scaling up, especially in Southeast China with a higher population density and less cultivated land. Currently, the common nitrogen fertilization for ratoon rice is concentrated within 20 days before and after the harvest of the main crop. However, this fertilization pattern may not be suitable for low stubble regenerative rice due to its extended growth period, leading to diminished nitrogen utilization efficiency and heightened greenhouse gas emissions, particularly nitrous oxide (N2O) emissions. It is imperative to explore a nitrogen fertilizer management model for clean production of low stubble ratoon rice (RR). In this study, we examined the effects of nitrogen fertilizer application rates and methods (single or split application) on yield and greenhouse gas emissions during the regrowth season. We employed a multi-criteria assessment approach combined with field measurements, energy analysis, environmental assessment, and economic evaluation on ratoon rice under various nitrogen fertilizer treatments. The results showed that the ratoon rice produced the highest total energy output under 67.5 N+22.5 N (Fertilize with 67.5 kg nitrogen ha−1 and 22.5 kg nitrogen ha−1 3 days after main season rice harvesting and during the heading stage of ratoon rice) treatment compared to the 90 N+0 N (conventional fertilization, apply 90 kg nitrogen ha−1 fertilizer 3 days after harvesting at once) treatment. It was also found that reducing nitrogen application during the tillering stage reduced CH4 emissions, fertilization during the heading stage of the ratoon rice did not increase CH4 emissions, Since fertilization during the heading stage of ratoon rice did not lead to an increase in the partitioning of photoassimilates (photosynthetic product assimilates) to the rhizosphere soil, significant differences in sugar and acetic acid levels were not observed in the rhizosphere soil. As a result, no change was found in the expression of the methanogenic mcrA gene in the microbial community. The study also demonstrated that the 67.5 N+22.5 N treatment was able to promote the absorption of nitrogen nutrients, reduction in N2O emissions by 16.61%, subsequently increasing resource use efficiency, final yield and net ecosystem economic benefit by 5.96%, 7.19% and 5.57%, respectively, thereby decreasing carbon and nitrogen footprints by 6.64% and 3.50% compared with the 90 N+0 N treatment in the ratoon rice. These results suggest that a reasonable ratoon rice cultivation scheme is a promising farming system that can simultaneously improve resource use efficiency and economic profits, reduce greenhouse gas emissions and environmental footprint, while still maintaining the high productivity in ratoon rice.