Nitrogen Partial Factor Productivity Research Articles

Coupling Effects of Nitrogen and Irrigation Levels on Growth Attributes, Nitrogen Use Efficiency, and Economics of Cotton.

Nitrogen (N) fertilization plays a pivotal role in physiomorphological attributes and yield formation of field-grown cotton (Gossypium hirsutum L.), but little is known of its interaction with irrigation levels. Therefore, this study was conducted with an objective of evaluating the impact of irrigation and nitrogen levels on growth attributes and nitrogen use efficiency of Bt cotton (Gossypium spp.) in the hot arid region. The experiment consisted of a factorial arrangement of three irrigation levels (200, 400, and 600 mm) and four nitrogen rates (0, 75, 150, and 225 kg ha–1) in a split-plot design with three replications. Nitrogen fertilization and irrigation levels influenced cotton growth attributes and yield. The highest leaf area index, dry matter accumulation, crop growth rate, and relative growth rate were achieved at 225 kg N ha–1 and irrigation level 600 mm as compared to other experimental treatments. Similarly, nitrogen uptake and content by seed, lint, and stalk and total nitrogen uptake recorded maximum at 225 kg N ha–1 and irrigation level 600 mm. Interestingly, the treatment of 600 mm of irrigation and 150 kg N ha–1 displayed significant increase in nitrogen use efficiency indices such as agronomic efficiency of nitrogen (AEN) and recovery efficiency of nitrogen (REN), while partial factor productivity of nitrogen (PFPN) and internal nitrogen use efficiency (iNUE) were significantly higher with application of 600 mm of irrigation and nitrogen application rate of 75 kg ha–1. Application of 600 mm of irrigation along with 225 kg N ha–1 resulted in significant increase in gross return, net return, and B:C ratio than any other treatment combinations. So, application of 600 mm of irrigation along with 225 kg N ha–1 could be recommended for achieving higher growth and yield, as well as profitability of Bt cotton under hot arid region and similar agroecologies.

Effects of plant density, nitrogen rate and supplemental irrigation on photosynthesis, root growth, seed yield and water-nitrogen use efficiency of soybean under ridge-furrow plastic mulching

The ridge-furrow plastic mulching system has been reported to increase crop yield and water-nitrogen use efficiency in semi-arid and semi-humid regions, but the effects of plant density, nitrogen (N) rate and supplemental irrigation on chlorophyll, photosynthesis, root growth and seed yield of soybean under ridge-furrow plastic mulching are poorly understood. A two-year field experiment (2019 and 2020) was conducted on soybean in a split-split plot design, with two plant densities (D16: 160,000 plants ha−1; D32: 320,000 plants ha−1) as main plots, two N rates (N30: 30 kg N ha−1; N60: 60 kg N ha−1) as sub plots, and two irrigation levels (W0: rainfed; W30: supplemental irrigation of 30 mm at the flowering-podding stage) as sub-sub plots. The results showed that plant density, N rate and supplemental irrigation had significant effects on leaf chlorophyll content, chlorophyll fluorescence parameters, photosynthesis, aboveground/root growth and seed yield. Increasing plant density enhanced leaf area index (LAI) by 31.9% and aboveground biomass (AGB) by 59.4%, seed yield by 27.4%, water use efficiency of seed yield (WUEs) by 27.9% and nitrogen partial factor productivity (NPFP) by 26.6%. Increasing N rate increased leaf chlorophyll content by 11.9% and photosynthetic rate by 5.5%, thereby increasing LAI by 11.5%, AGB by 10.3%, seed yield by 8.9% and WUEs by 8.2%. Supplemental irrigation increased chlorophyll content by 7.6% and photosynthetic rate by 3.7%, thereby increasing LAI by 4.7%, AGB by 11.0%, seed yield by 4.7% and NPFP by 4.0%, while supplemental irrigation only increased WUEs under D32. Compared with D16N30W0, D32N60W30 enhanced seed yield by 44.0% and WUEs by 37.0%, but reduced NPFP by 28.8%. Compared with D32N30W30, D32N60W30 increased both seed yield and WUEs by 8.5%, but it reduced NPFP by 45.5% with 100% higher N input. LAI, AGB, WUEs, NPFP and some leaf physiological (EXC, Chla/Chlb, EWTleaf and Ls) and root (TRLD, TRVD and TRSD) indexes were closely related to soybean yield. This study provides a better understanding how plant density, N rate and supplemental irrigation improved soybean productivity and water-nitrogen use efficiency by regulating chlorophyll, photosynthesis and aboveground/root growth.

Concurrent Improvement in Maize Grain Yield and Nitrogen Use Efficiency by Enhancing Inherent Soil Productivity.

Quantifying the relationships of maize yield and nitrogen use efficiency (NUE) to inherent soil productivity (ISP) could provide a theoretical basis for implementing strategies that concurrently narrow the yield gap, increase NUE, and improve soil quality. A field study under irrigation conditions was conducted at five locations with large differences in ISP (estimated by maize grain yield without using fertilizers) across various ecological regions in Inner Mongolia, China. Our results showed that the changes in maize yield and nitrogen partial factor productivity (PFPN) to ISP followed a linear-plateau model, with a common inflection point. When ISP was below 8.0 t ha–1, maize yield and PFPN were stagnating at a low level, due to a trade-off between the contribution of soil and chemical fertilizers to yield. When ISP exceeded 8.0 t ha–1, the contribution rate of soil to yield stabilized at 80%, resulting in a simultaneous increase in maize yield by 1.2 t ha–1 and PFPN by 4.6 kg kg–1, for increasing ISP at each t ha–1. Our results indicated that while keeping other management strategies unchanged, to increase maize yield and PFPN by 15% or further 30%, it is necessary to increase ISP to 9.3 and 10.4 t ha–1, respectively. In this scenario, N input will be reduced by 33.5 and 47.5%, and apparent N losses will be reduced by 11.7 and 21.5%, respectively. Therefore, enhancing ISP could lead to a simultaneous improvement in yield and NUE as well as strongly support the green development of maize production.

Comprehensive Evaluation on the Yield, Quality, and Water-Nitrogen Use Efficiency of Mountain Apple Under Surge-Root Irrigation in the Loess Plateau Based on the Improved TOPSIS Method

The purpose of this study was to know the controlling effects of water and nitrogen coupling on the yield, quality, and water-nitrogen utilization effectiveness of mountain apples under surge-root irrigation in the Loess Plateau. In order to optimize the water and nitrogen irrigation systems of superior quality and high yield, 7 years was selected for the mountain apple test material. The trial was designed with four tiers of irrigation, i.e., full irrigation (FI: 85–100% θf, where θf is the field capacity), light deficit irrigation (DIL: 70–85% θf), moderate deficit irrigation (DIM: 55–70% θf), and severe deficit irrigation (DIS: 40–55% θf) and three tiers of nitrogen, i.e., high nitrogen (NH: 600 kg ha–1), medium nitrogen (NM: 400 kg ha–1), and low nitrogen (NL: 200 kg ha–1). The subjective weight attained by the analytic hierarchy methods and the objective weight achieved by the enhanced coefficient of variation method were examined to find the comprehensive weight based on the notion of game hypothesis. Then, the weighted technique for order of preference by similarity to the ideal solution (TOPSIS) process was utilized to comprehensively assess the yield, quality, and water-nitrogen use efficiency of the apples, and a binary quadratic regression model was created between the comprehensive evaluation index and water-nitrogen inputs. The results showed that the effects of irrigation and nitrogen levels on the fruit yield, irrigation water use efficiency (IWUE), total water use efficiency (TWUE), nitrogen partial factor productivity (NPFP), and quality of mountain apples were significant (P < 0.05). The apple yield and TWUE first improved and then diminished with an escalating quantity of water-nitrogen inputs, the IWUE diminished with a boost in the irrigation quantity, the NPFP dwindled when the nitrogen amount was increased. The best water and nitrogen inputs for apple yield, quality, or water-nitrogen use efficiency were dissimilar. The best comprehensive evaluation index was DILNM treatment, and the worst comprehensive evaluation index was DISNL treatment, based on the TOPSIS system. The interval of irrigation and nitrogen attained from the mathematic model ranged in 95–115 mm and 470–575 kg ha–1, respectively. The outcome of this study may perhaps offer a theoretical basis for the scientific research of surge-root irrigation and the managing of mountain apple tree irrigation and fertilization in the Loess Plateau, China.

Lowering nitrogen rates under the system of rice intensification enhanced rice productivity and nitrogen use efficiency in irrigated lowland rice

Among the essential plant nutrients, nitrogen (N) is the most important and universally deficient in rice cropping systems worldwide. Despite different practices available for improvement of N management, nitrogen use efficiency (NUE) is still very low in rice, particularly under conventional management practices. This study was conducted to assess the effect of two crop management practices including the system of rice intensification (SRI) versus conventional management practices (CP) with four N application levels (60, 90, 120, and 150 kg N ha−1) and absolute control (i.e., without N application) on rice growth, grain yield, and NUE. Experiments were established in split-plot randomized complete block design in three replicates. Crop management practices and N levels were treated as the main effect of main-plots and sub-plots, respectively with replicate blocks treated as random factors. Results indicated that deploying of SRI increased rice grain yield by 17.5 and 52.4% during wet and dry seasons, respectively compared with the CP. Rice grain yield was significantly (p < 0.05) higher in SRI than in CP at all levels of N application compared. The application of N at 120 and 60 kg ha−1 resulted in the increase in rice grain yields by 49 and 46.5%, respectively, relative to the absolute control during wet and dry seasons. Nitrogen application had a significant effect (p < 0.05) on agronomic nitrogen use efficiency (ANUE) and partial factor productivity (PFP). Results also indicated that agronomic nitrogen use efficiency (ANUE) was higher (27.2 kg grain kg−1 N) during the wet season with an application of 60 kg N ha−1. Furthermore, higher ANUE (23.8 kg grain kg−1 N) was recorded during dry season with an application of 90 kg N ha−1. The significant (p < 0.05) interaction effects of treatments were recorded on PFP between SRI and 60 kg N ha−1 during the wet (116.7 kg grain kg−1 N) and dry (105.8 kg grain kg−1 N) seasons. This study revealed that ANUE and PFP decreased with N application at the levels of 120 and 150 kg N ha−1 under SRI and CP during the two cropping seasons. The findings of the present study provide potential information that rice grain yield and higher NUE could be achieved at low N inputs under SRI, and thus reducing costs resulted from fertilizer inputs without compromising other environmental benefits.

Interaction between soil water and fertilizer utilization on maize under plastic mulching in an arid irrigation region of China

Plastic film mulching (PM) has become a widely used cropping method in arid and semiarid areas. However, it is unknown how different PMs affect crop water and N utilization and their interaction under different N supplies. A two-year field experiment was conducted in the Hetao Irrigation District (HID), in northwest China. Following local irrigation practices, 500 mm border irrigation was used to grow spring maize over two growing seasons (2019 and 2020) with two N levels: high-N (225 kg N ha–1) and low-N (150 kg N ha–1). Combined with three mulching methods, the experiment had five treatments: (i) no mulching with high-N (control, CK), (ii) black plastic film with high-N (HB), (iii) transparent plastic film with high-N (HT), (iv) black plastic film with low-N (LB), and (v) transparent plastic film with low-N (LT). The 4 PM treatments had higher average soil water storage (0–120 cm) than CK. The PM treatments had the highest water consumption coefficients (Kwcn) at 6–leaf to 12–leaf stage (Kwc2) and milking to maturity (Kwc5) stage. The HP treatments (HB and HT) had higher soil nitrogen storage than CK during the growth period. Averaged across two seasons, HB and HT had 23.9%, 29.2% respectively, higher grain yields than CK. Averaged across two seasons, the transparent PM treatments had 7.49%, 5.31%, and 1.72% higher water use efficiency (WUE), partial factor productivity of nitrogen (PFPN), and harvest index, respectively, than the black PM treatments. The PM treatments showed the relationship between water use efficiency of biomass (WUEb) and nitrogen use efficiency of biomass (NUEb), with WUEb increased, NUEb also increased. Given these results, we recommend the high-N level and transparent PM for maize cropping to increase yield and resource utilization efficiency in the HID.

Grain Yield, Nitrogen Use Efficiency and Antioxidant Enzymes of Rice under Different Fertilizer N Inputs and Planting Density

Nitrogen fertilizer and planting density are key factors affecting rice yield and nitrogen utilization efficiency. There is still a need to optimize nitrogen fertilizer and planting density management for high yield. We studied the effects of different quantities of nitrogen application (N0 0 kg ha−1, N1 120 kg ha−1, N2 180 kg ha−1) and planting density (low-density: 18.8 hills m−2; high-density: 37.5 hills m−2) on rice yield, photosynthetic characteristics, antioxidant system, and nitrogen use efficiency. ANOVA results indicated that most tested traits were affected by environment, planting density, N application, and their interactions. Comparing the results of low-density planting, high-density planting increased the panicle number by 21.12% but decreased the grain number per panicle and yield by 3.97% and 22.48%, respectively. Similarly, the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities and PFPn (partial factor productivity of nitrogen) decreased by 8.20%, 6.99%, 16.41%, 14.28%, and 5.73%, respectively, while HIn (N harvest index) increased by 1.32%. Compared to no N application, N application treatments increased the panicle number, grain number per panicle, and yield by 9.92%, 17.64%, and 37.83% in the N1 treatment; and increased by 17.15%, 29.09%, and 128.94% in the N2 treatment, respectively. N application significantly increased net photosynthetic rates and enzyme activities of antioxidant antioxidases. Compared with N1, N2 decreased REn (apparent recovery efficiency of N), AEn (agronomic N use efficiency), and PFPn by 8.98%, 11.80%, and 25.14%, respectively, while, compared with N0, N1 increased HIn by 8.50%. It was observed that nitrogen fertilizer and planting density had an interaction effect on the net photosynthetic rate, antioxidant enzyme activities, and PFPn and HIn. Given a comprehensive consideration, it is best to apply nitrogen at a rate of 120 kg ha−1 at the planting density of 37.5 hills m−2 for high grain yield and high N use efficiency in our experimental site.

Optimising the root traits of summer maize to improve nutrient uptake and utilisation through rational application of urea ammonium nitrate solution

The production of summer maize is greatly affected by nitrogen (N) sources through regulating root growth and distribution. Four N treatments in the field experiment were designed as UAN (urea ammonium nitrate solution was applied under traditional side-dressing method), urea (urea was applied under traditional side-dressing method), UWFI (UAN was applied underwater and fertiliser integration technology) and CK (no N applied). The results showed that the root length density, surface area density and volume of DH605 (mid-late hybrid) and DH518 (mid-early hybrid) under UWFI were higher than other treatments, especially in shallow layers. The root absorption area of each soil layer under N application treatments varied with the growth stage. The grain yield and the accumulations of N, P and K in the shoots showed the trend of UWFI &amp;gt; UAN &amp;gt; urea &amp;gt; CK. Compared with UAN and urea, the nitrogen agronomic efficiency of UWFI treatment increased by 40.5~78.6%, and the nitrogen partial factor productivity increased by 4.75~7.61%. Consequently, rational application of UAN would improve root traits, nutrient uptake and utilisation, and yield of summer maize.

Effects of nitrogen application and brackish water irrigation on yield and quality of cotton

In order to alleviate the shortage of water resources for cotton (Gossypium hirsutum L.) planting in Xinjiang of China, a reasonable amount of nitrogen application under brackish water irrigation was sought. A two-year field experiment was conducted to investigate the effects of nitrogen application rate and irrigation water salinity on seed cotton yield, nitrogen partial factor productivity and fiber quality in Xinjiang under mulched drip irrigation in 2019 and 2020. In this study, we selected four nitrogen application rates (i.e., 100, 200, 300, and 400 kg N ha−1, respectively) and three irrigation water salinity (i.e., 1, 3, and 5 g L−1, respectively). Our results showed that nitrogen application rates and irrigation water salinity significantly affected the seed cotton yield, nitrogen partial factor productivity, micronaire, fiber length, fiber strength, uniformity index and elongation. As the salinity of irrigation water increased, seed cotton yield and nitrogen partial factor productivity increased first and then decreased, micronaire decreased, but fiber length, fiber strength, uniformity index and elongation increased. Moreover, seed cotton yield, micronaire, fiber length, fiber strength, uniformity index and elongation increased first and then decreased, and nitrogen partial factor productivity decreased with the amount of nitrogen application. The optimal combination of nitrogen application rate and irrigation water salinity were 200 kg N ha−1 and 5 g L−1 by principal component analysis. We concluded that the normalized relative value of seed cotton yield and comprehensive evaluation value was 0.85, when the nitrogen application rate and the irrigation water salinity were 197.04 ⁓ 237.94 kg N ha−1 and 3.60 ⁓ 3.88 g L−1, respectively.

Optimizing nitrogen fertilizer inputs and plant populations for greener wheat production with high yields and high efficiency in dryland areas

Bridging yield gaps in staple crops is widely reported as a highly efficient means for improving grain production. However, changes in production efficiency and the environmental footprint remain less investigated when narrowing these gaps. In this study, we collected data from 299 wheat plots on the Loess Plateau of China to identify changes in nitrogen efficiency, nutrient balance, and environmental risks when narrowing the yield gaps. The low-yielding (LY) and high-yielding (HY) plots had an average yield gap of 1936 kg ha–1 (33.5%) and nitrogen partial factor productivity gap of 10.3 kg kg–1 (30.1%) that were simultaneously narrowed under similar fertilizer inputs. Optimizing sowing date improved spikes per m2 (27.4%) and grains per head (12.9%), key measures to improving wheat grain yields. The high-yielding high-efficiency (HYHE) plots produced on average 43.0% and 14.6% higher nitrogen partial factor productivity and grain yield, respectively than the high-yielding low-efficiency (HYLE) plots. Appropriate nitrogen fertilizer inputs significantly enhanced nitrogen use efficiency and maintained grain yield on HY plots. Grain yield and nitrogen partial factor productivity gradually increased with year of cultivar release (1995–2019) (P < 0.05). However, soil organic matter, pH, available phosphorus, mineral nitrogen, and available potassium had no significant effect on grain yield or nitrogen use efficiency. The HYHE plots had the lowest nitrogen surplus (25 kg N ha–1), phosphorus surplus (31 kg P ha–1), and greenhouse gas emissions (2327 kg CO2-eq ha–1) of the surveyed plots. In the HY plots, moderate potassium fertilizer should be supplemented to balance wheat production. In conclusion, excellent cultivars and high plant density are key for bridging the yield gap between LY and HY plots. Optimizing fertilizer management could further promote HY plots from low to high production efficiency. This research provides farmers with the knowledge and methods to sustainably bridge field-level yield gaps in dryland wheat production.

Effects of soil preparation and mulching practices together with different urea applications on the water and nitrogen use of winter wheat in semi-humid and drought-prone areas

Soil preparation and mulching practices in combination with slow-release urea application are important measures for agricultural yield enhancement. However, slow-release urea may cause a yield reduction due to insufficient fertility in early crop growth. We considered whether the ridge-furrow plastic-mulching (RFP) system using different mulch colors could offset this disadvantage. An experiment was conducted using a randomized split-plot design with three soil preparation and mulching practices as the main-plot treatments in combination with three different urea applications as sub-plot treatments. The three soil preparation and mulching practices were flat cropping without mulch (F), the RFP system with white plastic mulch over the ridge (W), and the RFP system with black plastic mulch over the ridge (B); the three urea applications were no urea (N0), slow-release urea (NS), and ordinary urea (NU). The results showed that compared to F, the RFP system (especially B) could increase the use of precipitation and reduce soil water depletion, which ultimately increased the water productivity (WP) of winter wheat. In addition, the nitrogen use efficiency of NS was further improved under the RFP system, while there was essentially no difference between the two different urea types under F. In summary, B could take full advantage of NS to coordinate the relationship between effective spikes per unit area, grains per spike, and 1000-grain weight, maximizing the WP, nitrogen use efficiency, and grain yield. Between 2016 and 2019, the WP and grain yield of B-NS increased by 79.2–107.0% and 75.7–87.0%, respectively, compared to the lowest value (F-N0). The nitrogen agronomic efficiency (NAE), nitrogen physiological efficiency (NPE), nitrogen recovery efficiency (NRE), and nitrogen partial factor productivity (NPFP) of B-NS increased by 116.1–123.3%, 28.5–34.8%, 66.1–71.9%, and 44.1–53.2%, respectively, compared with the lowest value (F-NU).

Impacts of Slow-Release Nitrogen Fertilizer Rates on the Morpho-Physiological Traits, Yield, and Nitrogen Use Efficiency of Rice under Different Water Regimes

The efficient use of water and fertilizer is vital for optimizing plant growth and yield in rice production. To achieve sustainable rice production and resource management, the ways in which applied water and nitrogen affect the root and shoot morpho-physiology, as well as yield, must be understood. In this study, a pot experiment was conducted to investigate the effects of slow-release nitrogen fertilizer (sulfur-coated urea) application at three levels (light nitrogen (NL), medium nitrogen (NM), and heavy nitrogen (NH)) on the growth, yield, and nitrogen use efficiency (NUE) of rice grown under three water regimes (wetting and soil saturation (WSS), wetting and moderate drying (WMD) and wetting and severe drying (WSD)). The results revealed that differences in water regimes and fertilizer rates led to significant differences in the roots, shoots, yield, and NUE of rice. Increasing the N dosage by 5% enhanced the root and biomass production by 16% in comparison with that of the other groups. The NH×WSS treatment produced the greatest root length, weight, density, active absorption, and oxidation. However, the integration of WSS × NL generated the maximum value of nitrogen apparent recovery efficiency (63.1% to 67.6%) and the greatest value of nitrogen partial factor productivity (39.9 g g−1 to 41.13 g g−1). Transmission electron microscopy (TEM) images showed that plants grown under high and medium nitrogen fertilizer rates with WSS had improved leaf mesophyll structure with normal starch grains, clear cell walls, and well-developed chloroplasts with tidy and well-arranged thylakoids. These results show that TEM images are useful for characterizing the nitrogen and water status of leaves in the sub-micrometer range and providing specific information regarding the leaf microstructure. The findings of this study suggest that the application of NH×WSS can produce improvements in growth traits and increase rice yield; however, the NL×WSS treatment led to greater NUE, and the authors recommend its usage in rice agriculture.

Improvement in dryland crop performance and soil properties with multiple annual applications of lignite-derived humic amendment

Humic amendment (HA) is increasingly being evaluated and utilized to improve soil health and crop productivity in intensely farmed arid and semi-arid regions. However, the scientific comparison of field-scale use of single vs. repeated application of HA has not been reported. A field study was conducted to quantify the effect of different numbers of annual HA applications on (i) oat crop performance indicators, and (ii) the changes in soil health metrics in a dryland farming ecosystem. We found that multiple years of annual HA application improved crop growth, and increased grain protein yield (up to 60%), grain yield (21%), water use efficiency (22%), partial factor productivity of nitrogen (21%) and economic benefit (34%) over that for the control (no HA) during both a wetter and a drier growing season. The greater input of crop residue associated with higher yields led to an increase of soil organic carbon and water storage at both 0–20 and 20–60 cm soil layers, and a reduction in soil electrical conductivity, pH and bulk density with increasing years of HA application. There was an overall improvement in soil micro-environmental conditions. These in turn promoted an increased activity of the soil enzymes urease (up to 89%), invertase and catalase and soil nutrient turnover and availability (e.g. up to 58% higher plant available nitrogen). Our results show for the first time that repeated annual HA application of at least 2 years would be a cost-effective strategy to combat land degradation and nurture sustainable crop production in dryland agriculture under widely varying weather scenarios expected with climate change.

Grain Yield and Nitrogen Use Efficiency Vary with Cereal Crop Type and Nitrogen Fertilizer Rate in Ethiopia: A Meta-Analysis

The crop production in Ethiopia is markedly constrained by soil nutrient depletion and limited fertilizer input. Nitrogen is among the most yield-limiting factors of cereal crops, especially in sub-Saharan Africa (SSA). A meta-analysis of 82 studies was carried out to evaluate the response of major cereal crops, viz. wheat, maize, barley, teff, and sorghum, to nitrogen fertilization in Ethiopia. The results showed that N-application significantly increased yields of all the five crops examined herein. The average yields of the treatment effects over controls for the five crops were 3775.8 kg∙ha−1 and 2593.3 kg∙ha−1, respectively. The overall yield response to nitrogen treatments for all the crops was 64.8% (wheat, 96.5%; maize, 40.65%; barley 84.36%; teff, 50.48%; and sorghum; 23%). Overall, nitrogen agronomic efficiency (AEN) and partial factor productivity (PFPN) were 18.2 and 71.81 kg∙kg−1, respectively. A downtrend of nitrogen use efficiency with an increase in N rate was realized. The yield response was higher for the nitrogen treatment effects of >100 kg∙N∙ha−1 (123.9%), clay soils (75.46%), low initial soil organic carbon (SOC) and available phosphorous (AP) (92.4% and 101.6%), respectively, Therefore, we recommend the application of nitrogen fertilizer (>100 kg∙N∙ha−1), especially on infertile soils for improved grain yield and NUE in aforementioned cereal crops in Ethiopia and similar regions in sub-Saharan Africa (SSA).

Maize Nitrogen (N) Partial Factor Productivity, N Uptake and Utilization Efficiency, N vs. Yield and N vs. Evapotranspiration Relationships Response Under Center Pivot, Subsurface Drip and Surface (Furrow) Irrigation

Maize Nitrogen (N) Partial Factor Productivity, N Uptake and Utilization Efficiency, N vs. Yield and N vs. Evapotranspiration Relationships Response Under Center Pivot, Subsurface Drip and Surface (Furrow) Irrigation

Nutrient Response Functions of Sorghum for Miesso District Central Rift Valley of Ethiopia

This study was executed to offer the basis for optimized profit from fertilizer use for sorghum yield and to determine robust crop nutrient response function and economic rate for the production of sorghum at Miesso Central Rift Valley of Ethiopia. Trails were conducted at six experimental sites, sorghum yield response to N and P fertilizers application and economically optimum rates of nitrogen (EONR) and phosphorus (EOPR) were evaluated on a vertisols within the semi-arid Miesso districts west Hararge zone of Oromia region. The nutrient rates in 2014 cropping season four levels of Nitrogen (N) alone, these levels with 20 kg·ha−1 Phosphorus (P) and without N, 69 kg·ha−1 N with three levels of P treatments including the zero control were evaluated. In 2015, cropping season similar rates of N alone, the same rate N with 20 kg·ha−1 P, 92 kg·ha−1 N with three rates of P including the zero control were evaluated. The treatments were arranged in a randomized complete block with three replications in factorial design. Nutrient responses of sorghum were determined using asymptotic quadratic plateau functions. The significantly highest nitrogen rate was 46 kg·ha−1 alone in 2014 season, which gave grain yield of 2.56 Mg·ha−1 with a maximum yield advantage of 43%. P rates in both seasons and combined (sites + seasons) were not significantly influenced sorghum yield. Nitrogen agronomic and partial factor productivity peaked at 23 kg N ha−1 but declined with increasing N rate. The EONR combined (sites + seasons) were 37, 45, 52 and 60 kg·ha−1 and for the profit to cost ratio (PCR) were 2.43, 3.65, 4.86 and 5.79 at difference cost to grain price ratios (CP) = 3.6, 2.3, 1.6 and 1.2 respectively at Miesso Ethiopia. Nitrogen application had economically profitable than P. The study concluded that the application of N at 37 or 60 kg N ha−1 to sorghum production could be economically profitable for those economically constrained farmers or economically not constrained farmers. Validation should be farther conducted on farmers’ fields for refining the results obtained.

Maize productivity response to combined tillage and mulching in coastal saline zones

AbstractSoil salinization is threatening sustainable crop production in coastal saline regions. An integrated approach with combined tillage and mulching may be more successful than sole management practice (e.g., rotary tillage) for reducing soil salinity and improving crop productivity in coastal saline zones. We conducted a 3‐yr field experiment in maize (Zea mays L.) in the Yellow River Delta. We used four treatments: (a) rotary tillage to 15 cm (RT) (local farmers’ practice), (b) deep tillage to 25‐to‐30‐cm depth followed by RT (DT), (c) flat planting with the application of plastic mulch after DT (DM), and (d) ridge‐furrow planting together with plastic mulching after DT (DMF). These treatments were intended to improve soil properties and maize productivity, while increasing net returns. Grain yields were significantly increased by 18.5–20.9% under DMF and DM, nitrogen partial factor productivity (PFPN) by 18.5–20.8%, and net returns by US$103–124 ha–1, compared with RT. Grain yields with DMF and DM were also improved by 12.7–15.0%, PFPN by 12.8–15.0%, and net returns by $ 39–60 ha–1, compared with DT. Compared with RT, soil electrical conductivity (EC) and Na+ concentration with DMF and DM were reduced by 16.2–75.4% and 19.0–78.2%; EC and Na+ concentration were also reduced by 6.41–64.4% and 11.1–53.7%, compared with DT. These results demonstrate that combined tillage and mulching is an efficient integrated management approach for improving soil properties, promoting maize productivity, and increasing financial benefits in coastal saline zones.

Optimizing nitrogen distribution in source‐sink organs at heading for high grain yield and high nitrogen use efficiency in Japonica rice

AbstractJaponica rice (Oryza sativa L.) plants with large source (dry matter) and great sink (spikelets per unit area) have higher yield and nitrogen‐use efficiency (HYNUE) than Japonica rice plants with small source–sink characteristics. Nitrogen (N) distribution traits between source and sink organs at heading can be important HYNUE factors for Japonica rice. Two Japonica rice cultivars of Yongyou1540 (large source–sink sizes) and Zhendao18 (small source–sink sizes) were tested with N fertilizer treatments in field experiments. The results indicated that the N content ratios of source organs to panicle organ were increased with increasing N input for both cultivars. Moreover, the greater yield was associated with higher N content ratios of source organs to panicle organ across cultivars and N treatments. However, these parameters were negatively correlated with nitrogen partial factor productivity (PFPN) and nitrogen agronomic efficiency (NAE). Grain yield was positively determined by the ratio of nitrogen concentration in the leaf to nitrogen concentration in the panicle at heading (NcLPr.H). The nitrogen content distributed from the stem organ per spikelet (SSr) and N concentration in leaf organ were the main factors that negatively regulated PFPN and NAE, respectively. In addition, Yongyou1540 had a significantly higher NcLPr.H and lower SSr than Zhendao18 across N treatments (P &lt;.01), which explained why Yongyou1540 had a higher yield and greater PFPN than Zhendao18. These results implied that high NcLPr.H and low SSr may be key factors for the HYNUE formation in Japonica rice with a large source–sink cultivar.

Responses of yield, quality and water-nitrogen use efficiency of greenhouse sweet pepper to different drip fertigation regimes in Northwest China

Given water resources scarcity in Northwest China and the urgent need for the integration and optimization of scientific and technological resources in facility agriculture, this experiment explored the appropriate water and fertilizer management measures for greenhouse sweet pepper under fertilization in Northwest China. A two-year drip fertigation sweet pepper experiment was conducted in a solar greenhouse, with four irrigation levels (W1: 105% ETC, W2: 90% ETC, W3: 75% ETC, W4: 60% ETC) and four nitrogen levels (N1: 300 kg/ha, N2: 225 kg/ha, N3: 150 kg/ha, N4: 75 kg/ha). The results showed that above-ground dry matter accumulation (DMA), yield, harvest index (HI), and water use efficiency (WUE) of sweet pepper increased first and then decreased with the increase of irrigation/nitrogen amounts under the same nitrogen/irrigation levels. The partial factor productivity of nitrogen (PFPN) decreased significantly with the increase of nitrogen application rate, while it increased first and then decreased with the increase of irrigation level. The PFPN reached a peak at W2 level, despite no significant difference between W2 and W3 levels. With the increase of nitrogen application rate, soluble sugar and vitamin C content increased first and then decreased with a maximum at N3 level; nitrate content increased with the increase of nitrogen application rate, and there was no significant difference between N4 and N3 levels. The contents of soluble sugar and nitrate nitrogen decreased with the increase of irrigation amount, and they did not differ between W1 and W3 levels at N3 level; the vitamin C content increased first and then decreased with the increase of irrigation amount, reaching the maximum in W2 or W3 treatments. Considering the shortage of water resources in the study area, the W3N3 treatment (75% ETC, 150 kg/ha) could be recommended as the optimal drip fertigation strategy. Results showed that the optimal value of sweet pepper (the best confidence intervals of 85%) was achieved at the irrigation water and nitrogen amount of 78.2–80.8% ETC and 164.5–189.5 kg/ha, respectively. This study provides scientific basis for water and nitrogen management of high yield, quality, and benefit planting of facility sweet pepper in Northwest China.

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.