Nitrogen Partial Factor Productivity Research Articles

THE EFFICIENCY OF USING NITROGEN FERTILIZERS IN WHEAT CROP

Nitrogen has its undeniable role in increasing crop productivity and quality. However, used improperly, it can cause serious environmental damage. Increasing the efficiency of the use of chemical nitrogen fertilizers (NUE) is a goal of the future¸ necessary for a sustainable and competitive agriculture. The wheat crop studied is part of a long-term experiment, established in Lovrin in 1967. The experimental factors studied are: factor A - nitrogen, with the following graduations: N0, N30, N60, N90 and N120 and factor B - phosphorus, with the following graduations: P0, P40, P80, P120 and P160. From the combination of the two studied factors results 25 experimental variants, placed in the field according to the method of subdivided plots, in four repetitions. Chemical fertilizers with phosphorus - 46% superphosphate - were administered to the wheat crop in autumn and were incorporated under the basic plowing. Nitrogen fertilizers - 33.5% ammonium nitrate - were applied in fractions: 40% of the dose at start of vegetation, in the spring and 60% at straw elongation. The wheat culture is part of a three-year crop rotation - soybeans-wheat-corn. Following in rotation after soybeans, no nitrogen fertilizers were applied at the establishment of the crop. The variety studied is the Ciprian variety, created at SCDA Lovrin. For the evaluation of NUE, Plant N Uptake, Nitrogen Use Effciency and Partial Factor Productivity were analyzed in this paper. In the climatic conditions of the two experimental years, a distinctly significant positive correlation is established between the nitrogen dose administered and production, the value of the correlation coefficient being 0.56 **. Between the nitrogen dose, the protein content and the amount of protein per ha the correlation is very significant, with the following values ​​of the correlation coefficients: r = 0.96 *** (for protein) and r = 0.90 *** (for N uptake). Nitrogen use efficiency correlates negatively, very significantly, with the administered dose - r = -0.87 ***. This study also reveals the importance of phosphorus in the absorption and accumulation of nitrogen in wheat caryopsis. The amount of nitrogen accumulated increases with increasing dose of phosphorus, up to 80 kg ha-1, with the gradual reduction of the amount accumulated to high values ​​of phosphorus administered (120 kg ha-1 and 160 kg ha-1, respectively).

Optimal irrigation amount and nitrogen rate improved seed cotton yield while maintaining fiber quality of drip-fertigated cotton in northwest China

Improving the quality of cotton fiber is an important way to increase the competitiveness of cotton in the international market. However, how to improve fiber quality as much as possible without significantly reducing seed cotton yield is still a challenge to the cotton industry. A two-year field experiment was conducted in 2018 and 2019 to investigate the effects of irrigation amount and nitrogen rate on seed cotton yield and fiber quality traits of drip-fertigated cotton in northwest China. A comprehensive evaluation model was also developed to determine the optimal supply range of water and nitrogen to simultaneously improve seed cotton yield and fiber quality. There were four irrigation amounts (W0.6-60 % ETc, W0.8-80 % ETc, W1.0-100 % ETc and W1.2-120 % ETc, ETc was the crop evapotranspiration) and four nitrogen rates (N250-250 kg N ha−1, N300-300 kg N ha−1, N350-350 kg N ha−1 and N400-400 kg N ha−1). Increasing irrigation amount and nitrogen rate had positive effects on seed cotton yield. However, there was no significant difference in seed cotton yield between W1.0 and W1.2 and between N350 and N400. The optimal seed cotton yield was obtained under W1.0N350 in both 2018 (6655.58 kg ha−1) and 2019 (6309.3 kg ha−1). Water use efficiency (WUE) increased with the increase of nitrogen rate, and decreased with the increasing irrigation amount. Nitrogen partial factor productivity (PFPN) increased with the increase of irrigation amount, and decreased with the increasing nitrogen rate. There was a positive correlation between irrigation amount and fiber length, fiber strength, fiber quality index (FQI) and textile parameter, but a negative correlation with micronaire and short-fiber index. Fiber length, fiber strength, FQI and textile parameter first increased and then decreased with the increasing nitrogen rate. Irrigation amount and nitrogen rate had no significant effect on maturity index. There were strong correlations between the results of various evaluation methods, but the ranking differed among the methods. Based on the comprehensive evaluation model, the optimal combination of irrigation amount and nitrogen rate was W1.0N350. Through the combination of multiple regression and spatial analysis, the optimal supply range of irrigation amount of 334∼450 mm and nitrogen rate of 320∼400 kg ha−1was able to obtain over 90 % of the optimal seed cotton yield and 80 % of the optimal fiber quality.

QMrl-7B Enhances Root System, Biomass, Nitrogen Accumulation and Yield in Bread Wheat.

Genetic improvement of root systems is an efficient approach to improve yield potential and nitrogen use efficiency (NUE) of crops. QMrl-7B was a major stable quantitative trait locus (QTL) controlling the maximum root length in wheat (Triticum aestivum L). Two types of near isogenic lines (A-NILs with superior and B-NILs with inferior alleles) were used to specify the effects of QMrl-7B on root, grain output and nitrogen-related traits under both low nitrogen (LN) and high nitrogen (HN) environments. Trials in two consecutive growing seasons showed that the root traits, including root length (RL), root area (RA) and root dry weight (RDW), of the A-NILs were higher than those of the B-NILs at seedling stage (SS) before winter, jointing stage (JS), 10 days post anthesis (PA10) and maturity (MS), respectively. Under the LN environment, in particular, all the root traits showed significant differences between the two types of NILs (p < 0.05). In contrast, there were no critical differences in aerial biomass and aerial N accumulation (ANA) between the two types of NILs at SS and JS stages. At PA10 stage, the aerial biomass and ANA of the A-NILs were significantly higher than those of the B-NILs under both LN and HN environments (p < 0.05). At MS stage, the A-NILs also exhibited significantly higher thousand-grain weight (TGW), plot grain yield, harvest index (HI), grain N accumulation (GNA), nitrogen harvest index (NHI) and nitrogen partial factor productivity (NPFP) than the B-NILs under the corresponding environments (p < 0.05). In summary, the QMrl-7B A-NILs manifested larger root systems compared to the B-NILs which is favorable to N uptake and accumulation, and eventually enhanced grain production. This research provides valuable information for genetic improvement of root traits and breeding elite wheat varieties with high yield potential and NPFP.

Nitrogen Management Based on Visible/Near Infrared Spectroscopy in Pear Orchards

The timely estimation of nitrogen (N) requirements is essential for managing N fertilizer application in pear orchards. Visible/near infrared spectroscopy is a non-destructive and effective technique for real-time assessment of leaf N concentration, but its utility for decisions about fertilizer application in the pear orchards remains to be determined. In this study, we used leaf spectroscopy to determine leaf N concentration, used this value to calculate the amounts of N required for supplementary fertilization, and then evaluated the effects of the application. Over the two-year study, Cuiguan pear trees were treated with N at the following rates: 0 (N0), 100 (N1), 200 (N2), 300 (N3), and 400 (N4) g N per tree, regarded as five “controlled” N application rates. Another four “regulatory” treatments (Nr1-4) were fertilized as the “controlled” N application rates the first year, then given adjusted N application by topdressing as calculated using the N concentrations inferred from visible/near infrared spectroscopy data the second year. A model (R2 = 0.82) was established the first year to relate leaf spectra and N concentration using a partial least squares regression with full bands (350–2500 nm). The amount of N in the topdressing for the supplemental treatments was determined using the predicted leaf N concentration and the topdressing calculation method adapted from the N balance formula. Results showed that adjusted N applications of the Nr1 and Nr2 increased yield by 26% and 23%, respectively, over the controlled treatments N1 and N2. Although treatments Nr3 and Nr4 did not increase yield significantly over N3 and N4, the partial factor productivity of nitrogen in Nr4 was higher than the N4. The transverse diameter of fruit from Nr1 trees was significantly higher than from N1 trees, while the longitudinal diameter of fruit from Nr1, Nr2, and Nr3 trees was significantly higher than from N1, N2 and N3 trees, suggesting that fruit longitudinal growth and single-fruit weight is stimulated by adjusted N applications. However, the soluble solids in fruit from trees receiving adjusted N were not significantly greater than in fruit from non-supplemented trees. In conclusion, our results illustrate that regulatory N management contributes to fruit yield and quality especially in the nitrogen deficiency condition and improves the nitrogen use efficiency in nitrogen surplus. The N prediction model established using the nondestructive visible/near infrared spectroscopy is convenient and economical.

Improving winter wheat grain yield and water-/nitrogen-use efficiency by optimizing the micro-sprinkling irrigation amount and nitrogen application rate

Available irrigation resources are becoming increasingly scarce in the North China Plain (NCP), and nitrogen-use efficiency of crop production is also relatively low. Thus, it is imperative to improve the water-use efficiency (WUE) and nitrogen fertilizer productivity on the NCP. Here, we conducted a two-year field experiment to explore the effects of different irrigation amounts (S60, 60 mm; S90, 90 mm; S120, 120 mm; S150, 150 mm) and nitrogen application rates (150, 195 and 240 kg ha–1; denoted as N1, N2 and N3, respectively) under micro-sprinkling with water and nitrogen combined on the grain yield (GY), yield components, leaf area index (LAI), flag leaf chlorophyll content, dry matter accumulation (DM), WUE, and nitrogen partial factor productivity (NPFP). The results indicated that the GY and NPFP increased significantly with increasing irrigation amount, but there was no significant difference between S120 and S150; WUE significantly increased first but then decreased with increasing irrigation and S120 achieved the highest WUE. The increase in nitrogen was beneficial to improving the GY and WUE in S60 and S90, while the excessive nitrogen application (N3) significantly reduced the GY and WUE in S120 and S150 compared with those in the N2 treatment. The NPFP significantly decreased with increasing nitrogen rate under the same irrigation treatments. The synchronous increase in spike number (SN) and 1 000-grain weight (TWG) was the main reason for the large increase in GY by micro-sprinkling with increasing irrigation, and the differences in SN and TGW between S120 and S150 were small. Under S60 and S90, the TGW increased with increasing nitrogen application, which enhanced the GY, while N2 achieved the highest TWG in S120 and S150. At the filling stage, the LAI increased with increasing irrigation, and greater amounts of irrigation significantly increased the chlorophyll content in the flag leaf, which was instrumental in increasing DM after anthesis and increasing the TGW. Micro-sprinkling with increased amounts of irrigation or excessive nitrogen application decreased the WUE mainly due to the increase in total water consumption (ET) and the small increase or decrease in GY. Moreover, the increase in irrigation increased the total nitrogen accumulation or contents (TNC) of plants at maturity and reduced the residual nitrate-nitrogen in the soil (SNC), which was conducive to the increase in NPFP, but there was no significant difference in TNC between S120 and S150. Under the same irrigation treatments, an increase in nitrogen application significantly increased the residual SNC and decreased the NPFP. Overall, micro-sprinkling with 120 mm of irrigation and a total nitrogen application of 195 kg ha–1 can lead to increases in GY, WUE and NPFP on the NCP.

Effects of deep vertical rotary tillage on the grain yield and resource use efficiency of winter wheat in the Huang-Huai-Hai Plain of China

Tillage represents an important practice that is used to dynamically regulate soil properties, and affects the grain production process and resource use efficiency of crops. The objectives of this 3-year field study carried out in the Huang-Huai-Hai (HHH) Plain of China were to compare the effects of a new deep vertical rotary tillage (DVRT) with the conventional shallow rotary tillage (CT) on soil properties, winter wheat (Triticum aestivum L.) grain yield and water and nitrogen use efficiency at different productivity levels, and to identify a comprehensive management that optimizes both grain yield and resource use efficiency in the HHH Plain. A split-plot design was adopted in field experiments in the winter wheat growing seasons of 2016–2017 (S1), 2017–2018 (S2) and 2018–2019 (S3), with DVRT (conducted once in June 2016) and CT performed in the main plots. Subplots were treated with one of four targeted productivity level treatments (SH, the super high productivity level; HH, the high productivity and high efficiency productivity level; FP, the farmer productivity level; ISP, the inherent soil productivity level). The results showed that the soil bulk density was reduced and the soil water content at the anthesis stage was increased in all three years, which were due to the significant effects of DVRT. Compared with CT, grain yields, partial factor productivity of nitrogen (PFPN), and water use efficiency (WUE) under DVRT were increased by 22.0, 14.5 and 19.0%. Path analysis and direct correlation decomposition uncovered that grain yield variation of winter wheat was mostly contributed by the spike numbers per area under different tillage modes. General line model analysis revealed that tillage mode played a significant role on grain yield, PFPN and WUE not only as a single factor, but also along with other factors (year and productivity level) in interaction manners. In addition, PFPN and WUE were the highest in HH under DVRT in all three growth seasons. These results provided a theoretical basis and technical support for coordinating the high yield with high resource use efficiency of winter wheat in the resource-restricted region in the HHH Plain of China.

Modelling adaptation strategies to reduce adverse impacts of climate change on maize cropping system in Northeast China

Maize (Zea mays L.) production in Northeast China is vulnerable to climate change. Thus, exploring future adaptation measures for maize is crucial to developing sustainable agriculture to ensure food security. The current study was undertaken to evaluate the impacts of climate change on maize yield and partial factor productivity of nitrogen (PFPN) and explore potential adaptation strategies in Northeast China. The Decision Support System for Agrotechnology Transfer (DSSAT) model was calibrated and validated using the measurements from nine maize experiments. DSSAT performed well in simulating maize yield, biomass and N uptake for both calibration and validation periods (normalized root mean square error (nRMSE) < 10%, −5% < normalized average relative error (nARE) < 5% and index of agreement (d) > 0.8). Compared to the baseline (1980–2010), the average maize yields and PFPN would decrease by 7.6–32.1% and 3.6–14.0 kg N kg−1 respectively under future climate scenarios (2041–2070 and 2071–2100) without adaptation. Optimizing N application rate and timing, establishing rotation system with legumes, adjusting planting dates and breeding long-season cultivars could be effective adaptation strategies to climate change. This study demonstrated that optimizing agronomic crop management practices would assist to make policy development on mitigating the negative impacts of future climate change on maize production.

Experimental Study on the Optimal Threshold of Water and Nitrogen Quantities for Tomato Growth under the Irrigation with Biogas Slurry in Greenhouse

HighlightsApplication of biogas slurry can significantly improve the integrated growth, yield, quality of tomatoes.Water-nitrogen coupling model was established based on multi-index evaluation system of tomatoes.The optimal application quantitative range of water and nitrogen was obtained based on the water-nitrogen coupling model.Abstract. Biogas slurry, a liquid organic fertilizer, has been widely used in agricultural production. However, the characteristics of high water content and low fertility make it always applied empirically and a scientific and reasonable application of biogas slurry is urgent needed in practical agricultural production. This study aims to explore the effects of various biogas slurry concentrations on the yield, comprehensive nutritional quality (CNQ), irrigation water use efficiency (IWUE) and partial factor productivity of nitrogen (PFPN) of tomatoes in a greenhouse. Seven treatments, including T1(BS1:4; 0.8Ep), T2 (BS1:6; 0.8Ep), and T3(BS1:8; 0.8Ep), T4(BS1:4; 0.6Ep), T5(BS1:4; 1.0Ep), CK (no fertilization; 1.0Ep), CF (conventional chemical fertilization; 1.0Ep) were set up, where BS1:4, BS1:6,and BS1:8 are the volume ratio of biogas slurry to water, 0.6, 0.8, and 1.0 were crop dish coefficients, respectively. Ep is the evaporation amount of a 20 cm standard evaporating dish. The results showed that appropriate application of biogas slurry had a positive impact on crop growth such as total dry biomass, plant height, stem diameter and finally increased the yields, in which T1 treatment was the best. The fruit yield increased with the increase of biogas slurry ratio for treatments at the same irrigation level of 0.8Ep and the maximum yield of single tomato can reach 5.174 kg. The IWUE increased with the decrease of irrigation for treatments at the same biogas slurry ratio of BS1:4 and T4 treatment had the highest IWUE. The CNQ first increased and then decreased with the increase of biogas slurry ratio under the same irrigation level of 0.8Ep and T2 treatment obtained the highest CNQ; but the PFPN decreased with the increase of biogas slurry ratio and T3 treatment acquired the largest PFPN. Within an 80% confidence interval, when the irrigation amount was in a range of 39.233~43.134 L and the nitrogen quantities was 7.983~8.426 g, the yield, IWUE, CNQ, and PFPN can reach =80% of their maximums at the same time. Taking into account the growth, yield, fruit quality, and water and fertilizer use efficiency, T1 treatment was the best fertigation strategy for a higher production and better quality. The results can provide some help for scientific management of biogas slurry application in greenhouse. Keywords: Biogas slurry, Quality, Spatial analysis method, Tomato (Lycopersicum esculantum Mill), Yield.

Coupling effects of water and nitrogen on photosynthetic characteristics, nitrogen uptake, and yield of sunflower under drip irrigation in an oasis

An experiment was conducted in an oasis area in northwest China to assess the coupling effects of water and nitrogen supply through drip irrigation on photosynthetic characteristics, nitrogen uptake, and yield of sunflower (Helianthus annuus L.), as well as the nitrate distribution in the root-zone soil. The experiment included three irrigation levels (210 [W1], 300 [W2], and 390 [W3] mm), three nitrogen levels (162 [N1], 232 [N2], and 302 [N3] kg/hm2), and control treatment (no fertilization during whole growth period and only irrigated at the budding stage). A nitrogen content over-accumulation in the soil was observed under the low irrigation amount with high fertilizer supply, which cannot enhance the sunflowers’ absorption of nitrogen. Excessive irrigation caused leach of the soil nitrogen, reduced nitrogen content in the root-zone soil (0-40 cm) and limited nitrogen uptake by the crop. Although low irrigation amount with high fertilizer supply can increase the nitrogen content in the soil, it cannot enhance the sunflowers’ absorption of nitrogen. At the vegetative stage of sunflower growth, the accumulation of nitrogen in the organs was mainly concentrated in the leaves, while it was transferred to the flower disk at the reproductive growth stage. Reasonable coupling of water and nitrogen improved the transport of nitrogen from leaves and stems to the flower disk aromoted the formation of yield components. Six regression equations were established with irrigation and fertilization amount as independent variables, and seed rate, seed weight per flowerdisk, 1000 grain weight, yield, water use efficiency and nitrogen partial factor productivity as dependent variables, respectively. Multiple regression and spatial analysis suggested that the irrigation amount of 241.62- 253.35 mm and the fertilization application of 202.02-209.40 N kg/hm2 was a good irrigation strategy, under which all six factors exceed 75% of their maxima, and the yield of sunflower reached 3 229.3 kg/hm2. Keywords: fertilization, Helianthus annuus L., irrigation management, nitrogen transformation, nutrient uptake, Xinjiang DOI: 10.25165/j.ijabe.20211405.6399 Citation: Wang T Y, Wang Z H, Wu Q, Zhang J Z, Quan L S, Fan B H, et al. Coupling effects of water and nitrogen on photosynthetic characteristics, nitrogen uptake, and yield of sunflower under drip irrigation in an oasis. Int J Agric & Biol Eng, 2021; 14(5): 130–141.

Effect of Reducing Nitrogen and Applying Organic Fertilizer on Nitrogen Use Efficiency and Rice Yield in Red Soil Regions of the Southern China

To explore the amount of reducing N fertilizer, a 2-year field experiment was conducted to investigate the effects of reducing N fertilizer and applying organic fertilizer on nitrogen use efficiency (NUE) and rice yield in red soil regions of the Southern China. On the basis of applying 4500 kg/ha organic fertilizer and local custom fertilization with 204 kg/ha urea application, five treatments including no nitrogen fertilization (CK), local customary nitrogen application (N100), and nitrogen reduction of 10% (N90), 20% (N80), and 30% (N70) were conducted. The results showed that nitrogen agronomic efficiency (NAE), nitrogen recovery efficiency (NRE), nitrogen physiological efficiency (NPE) and nitrogen partial factor productivity (NPFP) of N90 treatment were significantly higher than those of other treatments, and the yield was as high as 9.33 t/ha, which showed a significant differences compared with CK and N100. The output value, benefit, and benefit-cost ratio of N90 were significantly higher than those of N100, which increased by 6.38%, 6.42%, 8.35%, and 8.20%, respectively. In addition, while applying the same amount of organic fertilizer, the rate of nitrogen reduction has little effect on the soil organic matter content, meaning that N90 can achieve high NUE and high yield in rice. It is good to provide the theory basis for fertilizer decision-making in practice.

Optimization of water and nitrogen management for surge-root irrigated apple trees in the Loess Plateau of China

The Loess Plateau is one of the main regions for growing apple trees in China, but a shortage of water resources and low utilization of nitrogen have restricted its agricultural development. A 2-year field experiment was conducted which included three levels of soil water content (SWC), 90–75%, 75–60%, and 60–45% of field capacity, and five levels of nitrogen application (Napp), 0.7, 0.6, 0.5, 0.4 and 0.3 kg/plant. The treatments were arranged in a strip-plot design with complete randomized blocks with three replications. For both years, the water and Napp had significant (P<0.05) effects on leaf area index (LAI), yield, water use efficiency (WUE) and nitrogen partial factor productivity (NPFP) while the interaction effect of water and Napp on yield, WUE and NPFP was significant (P<0.05) in 2018, and not in 2017. For the same SWC level, WUE first increased, then decreased as Napp increased, while NPFP tended to decrease, but the trend of LAI with different Napp was closely related to SWC. At the same Napp, the LAI increased as SWC increased, while the WUE and NPFP first increased, then decreased, but the yield showed different trends as the SWC increased. The dualistic and quadric regression equations of water and Napp indicate that the yield, WUE and NPFP cannot reach the maximum at the same time. Considering the coupling effects of water and Napp on yield, WUE and NPFP in 2017 and 2018, the SWC level shall be controlled in 75–60% of field capacity and the Napp is 0.45 kg/plant, which can be as the suitable strategy of water and Napp management for the maximum comprehensive benefits of yield, WUE and NPFP for apple trees in the Loess Plateau and other regions with similar environments.

Evaluation of resource and energy utilization, environmental and economic benefits of rice water-saving irrigation technologies in a rice-wheat rotation system

Currently, numerous challenges such as excessive irrigation water consumption, labor shortage, lower economic and environmental benefits pose serious threats to rice cultivation systems. Therefore, more water- and labor-efficient irrigation technologies are needed in rice production for minimal environmental hazards and greater economic benefits. After the screening experiment of water-saving cultivation technologies and cultivars, a two-year field experiment was conducted to further explore the effects of efficient water-saving technologies and rice cultivars on the comprehensive benefits, global warming potential (GWP), grain yield, economic benefits, water productivity, nitrogen partial factor productivity, radiation, accumulated temperature and energy use efficiency (EUE) of a rice-wheat rotation system. Conventional flooding irrigation (F), intermittent irrigation (IR), transplanting rainfed (TR) and rice dry cultivation (D) were implemented with two rice cultivars, including Hanyou73 (HY) and Huanghuazhan (HH). After rice harvest, a winter wheat cultivar (Huamai 2566) was planted with traditional methods. The system of rice dry cultivation and wheat rotation had higher comprehensive benefits, which were attributed to greater water productivity, economic benefits and EUE and lower GWP, especially in the rice growing season. D treatment enhanced the comprehensive and economic benefits by 2.5% and 26.8%, 1.6% and 11.3%, 3.3% and 0.6%, and reduced the GWP by 3.4%, 56.7% and 30.2% compared with F, IR and TR treatments in the rotation system, respectively. During the rice season, D treatment significantly (P < 0.05) increased the economic benefits, water productivity and EUE, but slight decreased the grain yield than other treatments. Overall, rice dry cultivation (especially with the HY cultivar) can achieve higher comprehensive benefits in rice growing season as well as in the whole rotation system.

Optimizing nitrogen application for drip-irrigated winter wheat using the DSSAT-CERES-Wheat model

Improper application of nitrogen fertilizer for winter wheat production in the North China Plain (NCP) limits N use efficiency and increases the risk of non-point pollution. Crop simulation models may help with the assessment of N fertilizer management, to improve nitrogen use efficiency and to mitigate environmental pollution. In this study, the DSSAT-CERES-Wheat model was calibrated and validated with two-year field experiment, which coupled with five N rates (0, 120, 180, 240, and 300 kg ha−1) and three irrigation levels (40, 30, and 20 mm per irrigation) under drip irrigation. The calibrated DSSAT-CERES-Wheat model performed well in simulating the anthesis date (nRMSE=1.47%, d=0.89), maturity date (nRMSE=0.97%, d=0.92), shoot biomass (nRMSE=10.97%, d=0.92), grain yield (nRMSE=6.19%, d=0.96), and actual evapotranspiration (nRMSE=9.96%, d=0.76) of drip-irrigated winter wheat in two years. The calibrated model was subsequently used to evaluate drip-irrigated winter wheat production in response to six N rates (0, 120, 180, 240, 300, and 360 kg ha−1) under 40 meteorological scenarios, and the results showed that grain yields, water use efficiency, irrigation water use efficiency, and net margins increased with increasing N application rates until it reached 180 kg ha−1. Above 180 kg ha−1, negligible changes were measured in these values as the N rate increased. The nitrogen physiological efficiency and nitrogen partial factor productivity were greatly improved at a N rate of 180 kg ha−1, compared with those at a N rate of 240, 300, and 360 kg ha−1. Consequently, N rate of 180 kg ha−1 was the optimal nitrogen application rate for drip-irrigated winter wheat production. These results may provide a scientific basis for nitrogen management of drip-irrigated winter wheat in the NCP.

Effect of precision nitrogen management on yield and nitrogen use efficiency in different varieties of wheat (Triticum aestivum)

A field experiment was conducted during two consecutive winter (rabi) seasons of years 2015-16 and 2016-17 to study the effect of different nitrogen scheduling on yield and nitrogen use efficiency of different varieties of wheat (Triticum aestivum L.). The experiment was laid out in split-plot design with three replications; in which three varieties (viz. HUW 234, K 0307 and HD 2967) were planted in main plots. The combinations of 6 nitrogen scheduling practices which included different N application rates from 0 to 150 kg/ha in various split doses along with the use of LCC and Greenseeker was planned in sub plots. Results reveal that the yield attributing characters, grain yield, straw yield and biological yield were recorded significantly highest in HD 2967 as compared to other varieties. Whereas, varietal parameter did not significantly influence the agronomic efficiency, recovery efficiency and nitrogen harvest. Among nitrogen scheduling, application of 150 kg N/ha in three equal splits recorded significantly higher yield attributes, grain yield (4.70 and 4.81 t/ha), straw yield, biological yield, harvest index, and recovery efficiency of nitrogen. Greenseeker based nitrogen application recorded significantly highest agronomic efficiency and partial factor productivity of nitrogen.

Varied previous crops on improving oilseed flax productivity in semiarid Loess Plateau in China

To investigate the effects of crop rotation on oilseed flax growth and yield, three season experiments were carried out in semi-arid area of Dingxi, Gansu from 2017 to 2019. The designed 6 rotational systems were FFF (flax-flax-flax), PFF (potato-flax-flax), WPF (wheat-potato-flax), FPF (flax-potato-flax), PWF (potato-wheat-flax) and FWF (flax-wheat-flax). Flax growth and yield investigation results showed that crop rotation increased leaf area duration, dry matter accumulation, seed nitrogen accumulation, water and nitrogen used efficiency, compared with continuous cropping of flax. Flaxseed yields in rotation systems were 22.23%–44.11% greater than those of continuous cropping system. Those in wheat and potato stubbles had higher tiller number (21.43% and 29.46%), more branches (14.24% and 6.97%), effective capsules (26.35% and 28.79%), higher water use efficiency (40.26% and 33.5%), higher nitrogen partial factor productivity (33.85% and 31.46%) and dry matter (41.98% and 25.47%) than those in oilseed flax stubble. It concluded that crop rotation system was an effective measure for oilseed flax productivity in semi-arid area by improving yield components and promoting biomass.

Deep placement of mixed controlled-release and conventional urea improves grain yield, nitrogen use efficiency of rainfed spring maize

ABSTRACT Controlled-release urea (CRU) mixed with conventional urea can promote grain yield (GY). Whether the deep placement of mixed nitrogen fertilizer can further enhance GY, nitrogen use efficiency is rarely reported. In this study, four CRU-urea mixtures and two fertilizer placement depths were tested on rainfed spring maize. Fertilizer placement at a depth of 16 cm created a soil environment of lower temperature and higher water content than that at a depth of 8 cm. Increasing the fertilizer depth or the CRU ratio increased DM and total plant N content at maturity but lowered N remobilization efficiency (NRE) and DW remobilization efficiency (DRE). Maximum GY and partial factor productivity of nitrogen (PFPN) were achieved when CRU and urea were mixed at a ratio (1:0 and 2:1) and the fertilizer was placed at a depth of 16 cm. Although fertilizer deep placement increased production inputs, the increase in net benefits was even more dramatic, especially when CRU was mixed with urea. In summary, a 2:1 mixture of CRU and conventional urea is the most promising fertilization strategy for spring maize production, particularly when combined with 16 cm deep fertilizer placement.

Carbon footprint of a typical pomelo production region in China based on farm survey data

Greenhouse gas emissions are a central environmental concern in China, and quantifying the carbon footprint of crop production can help identify key options for mitigating greenhouse gas emissions from agriculture. Using two-year farm survey data from a typical pomelo production area in China, the carbon footprint of a pomelo orchard was assessed by quantifying the greenhouse gas emissions from farming inputs and operations with a full life cycle assessment methodology. The carbon emission and carbon sequestration levels were 19.9 and 3.43 t CO2 eq ha−1, respectively. The farm carbon footprint and product carbon footprint were 16.5 t CO2 eq ha−1 and 0.33 t CO2 eq t−1, respectively, which were 3.8 and 1.5 times greater than the corresponding mean values for other fruit orchards in different areas of the world. Compared with farms with low yield and high carbon footprint, farms with high yield and low carbon footprint reduced nitrogen fertilizer input significantly, by 44.7%. Furthermore, the yield of farms which with high yield and low carbon footprint increased significantly by 69.4%, and the farm carbon footprint and product carbon footprint significantly decreased by 40.7% and 67.2%, respectively, compared to those of farms with low yield and high carbon footprint. The synthetic nitrogen fertilizer application rate was significantly linearly correlated with, and contributed 84.7% to the carbon footprint of pomelo production. The relationships between the carbon footprint and the nitrogen partial factor productivity also indicated that improving nitrogen utilization can effectively reduce greenhouse gas emissions. In addition, based on group analysis, the difference in carbon footprint among farm groups was also mainly due to nitrogen fertilization. Reducing costs can significantly improve carbon efficiency without affecting the economic benefit at similar yield levels. Therefore, the carbon intensity of pomelo production in China could be reduced primarily by reducing excessive nitrogen fertilizer application and potentially increasing nitrogen use efficiency. Apart from this, these differences could be implemented by modifying farming fertilization strategies and farm size. Overall, this study highlights the importance of strengthening nitrogen management in pomelo production based on agricultural practices as well as upscaling farm size, which could achieve higher yields with lower greenhouse gas emissions and thereby avoid tradeoffs between productivity and carbon costs.

Roles of Nitrogen Deep Placement on Grain Yield, Nitrogen Use Efficiency, and Antioxidant Enzyme Activities in Mechanical Pot-Seedling Transplanting Rice

Mechanical pot-seedling transplanting (PST) is an efficient transplanting method and deep nitrogen fertilization has the advantage of increasing nitrogen use efficiency. However, little information is available about the effect of PST when coupled with mechanized deep nitrogen (N) fertilization on grain yield, nitrogen use efficiency, and antioxidant enzyme activities in rice. A two-year field experiment was performed to evaluate the effect of PST coupled with deep N fertilization in both early seasons (March–July) of 2018 and 2019. All seedlings were transplanted by PST and three treatments were designed as follows. There was a mechanized deep placement of all fertilizer (MAF), broadcasting fertilizer (BF), no fertilizer (N0). MAF significantly increased grain yield by 52.7%. Total nitrogen accumulation (TNA) was enhanced by 27.7%, nitrogen partial factor productivity (NPFP) was enhanced by 51.4%. nitrogen recovery efficiency (NRE) by 123.7%, and nitrogen agronomic efficiency (NAE) was enhanced by 104.3%, compared with BF treatment. Moreover, MAF significantly improved peroxidase (POD), catalase (CAT), and notably reduced the malonic dialdehyde (MDA) content for both rice cultivars, compared to BF. Hence, the result shows that mechanical pot-seedling transplanting coupled with nitrogen deep placement is an efficient method with the increase of grain yield and nitrogen use efficiency in rice cultivation in South China.

Evaluation of subsurface, mulched and non-mulched surface drip irrigation for maize production and economic benefits in northeast China

Drip irrigation is now commonly used for maize cultivation in China and other regions of the globe. The goal of this study was to compare water and fertilizer use as well as economic benefits for surface and subsurface drip irrigation and for mulched and non-mulched maize production in northeast China. An experiment was conducted during 2015 and 2016 in Chifeng in Inner Mongolia, China that included the following treatments mulched surface drip irrigation (M-DI), non-mulched surface drip irrigation (NM-DI); non-mulched subsurface drip irrigation (NM-SDI), and mulched furrow irrigation (M-FI). The results indicated that film mulching obviously improved the soil temperature and water content during the early growth period, which hastened maize emergence and growth. Compared with the M-FI treatment, the DI techniques significantly decreased the cost of field management and improved water and nitrogen use. The water use efficiency (WUE) and nitrogen partial factor productivity for DI treatments increased by 13.9–39.2% and 16.3–28.1%, respectively, on average for two years, compared to those for the M-FI treatment. The advantages of M-DI were film mulching and in-season fertigation, which improved maize development and achieved the highest yield and net output values, which were 9.2–10.1% and 4.7–19.1% higher than other techniques. The NM-SDI technique is a competitive viable alternative for maize cultivation given the lack of film residue, the ease of field management, which made the annual allocated cost of system decrease by 13.2–24.1% compared with others, and the highest WUE among the treatments. Therefore, the DI techniques showed potential to enhance maize production, but decisions regarding the use of DI should take both economic benefits and environmental impact into consideration.

Optimizing planting density to improve nitrogen use of super high‐yield maize

AbstractHigh grain yield and N use efficiency are key goals of crop production. Increasing planting density and supplying adequate N application are important agronomic practices to increase maize grain yield. However, little is known about the interaction between the planting density and N application rate of high‐yield maize under mulch drip irrigation. The objectives of this study were to determine the impacts of planting density and N application rate on the grain yield, economic return, nitrogen partial factor productivity (PFPN), and nitrogen agronomic efficiency (AEN) of super high‐yield maize under mulch drip irrigation in Northwest China. To achieve this, field experiments were conducted in 2017 and 2018 in Qitai farm, Xinjiang. The experiments included four N application levels−no nitrogen (N0), and 270 (N1), 360 (N2), and 450 kg N ha−1 (N3)−and five planting densities−7.5 (D1), 9.0 (D2), 10.5 (D3), 12.0 (D4), and 13.5 plants m−2 (D5). It was found that the N2D4 treatment obtained the highest grain yield (21.5−21.6 t ha−1) and economic return (US$3,399.7−$3,440.3 ha−1) and the relative higher PFPN (59.7−60.1 kg kg−1) and AEN (23.7−25.1 kg kg−1). The PFPN and AEN declined with increasing N application and varied according to a quadratic relationship with increasing planting density. Therefore, a reasonable increase of planting density and an appropriate reduction of N application combined with integrated irrigation−fertilization technology under mulch drip irrigation cannot only obtain high maize yield and economic return but can also improve the N utilization efficiency.