Maize Nitrogen Uptake Research Articles

Pengaruh Pemberian Berbagai Macam Bahan Organik terhadap Ketersediaan Hara Nitrogen, Fosfor dan Kalium serta Serapan Nitrogen oleh Jagung (Zea mays L.) pada Tanah Ultisols

Ultisols distributes spreadly in Indonesia, but this soil has low fertility. Therefore, the application of organic matter (OM) is a common management to increase this soil fertility. The purpose of this study was to determine the role of different types of OM (originated from animals and plants) on the availability of nitrogen, phosphorus, and potassium as well as nitrogen uptake in maize in Ultisols. Soil with a mass of 5 kg without organic matter (control), with the application of chicken manure, cow manure, swallow manure, kirinyuh, babadotan, and kalopo manure were incubated in experimental pots for two weeks at 60% field capacity. After the completion of the incubation period, soil sub-sampling was carried out for the determination of available N, available P and exchangeable K. Furthermore, in each experimental pot, corn seeds were planted, and the observations of dried-weight of corn and nitrogen uptake in corn were observed in a vegetative phase. The results showed that the application of different types of organic matter increased soil pH, nitrate content, exchangeable K, plant dried-weight and plant nitrogen uptake. The content of ammonium and available P was not affected by OM addition. The results also showed that OM derived from animals resulted in higher increases in pH and exchangeable K than those derived from plants. However, OM derived from plants resulted in higher increases in nitrate, plant dry weight and better plant N uptake than OM from animal waste. The results of this study show that the application of OM results in increases in some soil chemical properties, in which the degree of increases in soil chemical characteristics is controlled by the OM origin.

The Impact of Fertilizer Type on Dry Matter, Nitrogen Partitioning, and Yield of Spring Maize with Film-Side Sowing

Dry matter (DM) and nitrogen (N) transport from nutritive organs to the grain is critical for cereal crop yield and protein content. There is limited research on the effects of slow-release or controlled-release fertilizers on dry matter and nitrogen partitioning in the nutrient organs of spring corn. A field trial was conducted in the National Corn Industry Technology System Xinzhou Comprehensive Experiment Station, China. The effects of different fertilizer management on yield, photosynthetic capacity, and nutrient partitioning of spring maize were studied. We modeled local farmers’ planting and management practices (T3). Based on T3, we added a slow-release compound fertilizer (T2), which does not require a follow-up fertilizer, and a controlled-release formulated fertilizer (T1), which is highly efficient and has low carbon emissions. The net photosynthetic rate (Pn), transpiration rate (E), stomatal conductance (Gs), and intercellular CO2 concentration (Ci) were 23%, 18.5%, 18%, 10.5% and 19%, 10.9%, 7%, and 5.5% higher in T1 compared to those of T3 and T2, respectively, at the ripening stage. The contribution of post-flowering DM transport to the kernel of T1 was 46% and 41.4% higher than that of T3 and T2, respectively. The nitrogen content of the kernel of T1 was 35.2% and 18.5% higher than that of T3 and T2, respectively. After a comprehensive analysis, T1 prolonged the photosynthetic effect through adequate nitrogen supply, provided nutrients to the kernel, promoted maize nitrogen uptake and utilization, and ultimately improved yield.

Maize genotypes regulate the feedbacks between maize nitrogen uptake and soil nitrogen transformations

Maize (Zea mays L.) genotypes can directly affect gene expression and nitrogen (N) uptake capacity. However, the feedback between maize genotypes and soil gross N transformations, and their regulations on N uptake capacity are not well known. So, 15N tracing pot experiments were conducted in an acidic soil and an alkaline soil with six maize genotypes, i.e. Dika 007 (DK), Zhengda 999 (ZD1), Zhengdan 958 (ZD2), Jingke 968 (JK), Longdan 339 (LD), Liangyu 99 (LY). Maize N uptake and soil gross N transformation rates were quantified by the Ntraceplant tool to identify feedbacks between maize genotypes N uptake and soil N transformations and their mechanisms. Maize total N uptake rates (UTN) varied among genotypes and soils. UTN in alkaline soil was 1.1–2.1 times higher than that in acidic soil. NH4+ and NO3− uptake rates (UNH4 and UNO3, respectively) were regulated by specific N transport genes in acidic soil, supported by positive relationships between N uptake rates and relative expression of ZmNRT1.1, ZmNRT1.2 and ZmAMT1.1A genes. UTN, and UNO3 were positively correlated to soil gross N mineralization (M), and autotrophic nitrification (ONH4) rates, respectively. However, maize inhibited M compared to treatment without maize plantation (CK) due to effects on soil microbial community, and based on random forest analysis, the declined relative abundance of Acidicaldub, Gonytrichum and Nigrospora in acidic soil, Taeniolella in alkaline soil may cause the decrease of M by the presence of maize. Meanwhile, maize inhibited ONH4 to increase NH4+ residence time, which in turn was responsible for the positive relationship between UNH4 and ONH4. In contrast, the stimulation of heterotrophic nitrification (ONrec) by plants improved the NO3− availability. The maize genotypes, such as JK, could largely enhance N uptake by regulating the expression level of N transport genes in maize and stimulating soil N transformation to produce more inorganic N (Nmin) in the different soils. Our findings show that maize genotypes play a central role in regulating these feedbacks. These results are important for maize breeding and enhancing maize production.

Evaluating the influence of straw mulching and intercropping on nitrogen uptake, crop growth, and yield performance in maize and soybean.

Intercropping and straw mulching are sustainable agricultural practices that can positively affect crop growth and development, especially together. A split-plot experimental design was used to investigate the effects of intercropping and straw mulching on crop growth, crop yield, nitrogen uptake, and photosynthetic characteristics. The main plot focused on three planting patterns: soybean monoculture (S), maize monoculture (M), and maize/soybean intercropping (I). The subplot structure consisted of four levels of straw mulching (0, 4.8, 7.2, 9.6t ha-1). Interaction and variance analyses showed that straw mulching, intercropping, and their interaction had significant effects on plant height, stem diameter, leaf area index, chlorophyll content, nitrogen uptake, photosynthetic characteristics, and crop yield. Based on two-year averages for maize and soybean, the net photosynthetic rate (Pn) was up to 51.6% higher, stomatal conductance (Sc) was up to 44.0% higher, transpiration rate (Tr) was up to 46.6% higher, and intercellular carbon dioxide concentration (Ci) was up to 25.7% lower relative to no mulching. The maximum increases of Pn, Sc, and Tr of intercropped maize were 15.48%, 17.28%, and 23.94%, respectively, and the maximum Ci was 17.75% lower than that of monoculture maize. The maximum increase of Pn, Sc, and Tr of monoculture soybean was 24.58%, 16.90%, and 17.91%, respectively, and the maximum Ci was 13.85% lower than that of intercropped soybean. The nitrogen uptake of maize and soybean in the mulching treatment was 24.3% higher than that in the non-mulching treatment; the nitrogen uptake of intercropped maize was 34.2% higher than that of monoculture maize, and the nitrogen uptake of monoculture soybean was 15.0% higher than that of intercropped soybean. The yield of maize and soybean in the mulching treatment was 66.6% higher than that in the non-mulching treatment, the maize yield under intercropping was 15.4% higher than that under monoculture, and the yield of monoculture soybean was 9.03% higher than that of intercropped soybean. The growth index and photosynthesis of crops are important parts of yield formation. The results of this study confirmed that straw mulching, intercropping, and their interaction can ultimately increase crop yield by improving crop growth, nitrogen uptake, and photosynthesis. This result can be used as the theoretical basis for the combined application of these measures in agriculture.

Combinatorial Effects of Glycine and Inorganic Nitrogen on Root Growth and Nitrogen Nutrition in Maize (Zea mays L.)

Organic and inorganic nitrogen play important roles in plant nitrogen nutrition. However, how the coapplication of organic and inorganic nitrogen affects root growth, plant nitrogen metabolism, and soil nitrogen content is still unclear. Plant shoot and root growth, nitrogen uptake and metabolism, and soil nitrogen content were studied in maize (Zea mays L.) through pot experiments with different nitrogen treatments, including NH4+ -N (Amm), NO3− -N (Nit), NH4+ -N + NO3− -N (Amm + Nit), NH4+ -N + NO3− -N + glutamate-N (Amm + Nit + Glu), and NH4+ -N + NO3− -N + glycine-N (Amm + Nit + Gly). The results show that the shoot nitrogen uptake of maize treated with Amm + Nit + Gly was the highest among all the nitrogen treatments. In addition, the coapplication of glycine and inorganic nitrogen increased glutamine synthetase (GS) activity in the maize leaves, promoted nitrogen metabolism levels, and was conducive to the accumulation of amino acids and soluble protein in leaves. Compared with inorganic nitrogen, glycine combined with inorganic nitrogen increased the total root length and root surface area. A correlation analysis showed that total root length and root surface area had a significant positive effect on nitrogen uptake. When ammonium, nitrate, and glycine were applied together, the content of inorganic nitrogen and total nitrogen in soil was higher than that for other inorganic nitrogen treatments. Therefore, we conclude that glycine combined with inorganic nitrogen can increase soil nitrogen content, promote maize root growth, and thus facilitate nitrogen uptake and metabolism.

Maize nitrogen uptake, grain nitrogen concentration and root-zone residual nitrate nitrogen response under center pivot, subsurface drip and surface (furrow) irrigation

Maize nitrogen uptake, grain nitrogen concentration and root-zone residual nitrate nitrogen response under center pivot, subsurface drip and surface (furrow) irrigation

Maize nitrogen uptake and use efficiency, partial factor productivity of nitrogen, and yield response to different nitrogen and water applications under three irrigation methods

AbstractThe effects of irrigation and nitrogen (N) on grain yield, actual crop evapotranspiration (ETa), N uptake efficiency (NUE), partial factor productivity of N (PFPN), and N utilization efficiency (NUtE) of maize (Zea mays L.) under centre pivot (CP), subsurface drip (SDI) and gravity (furrow) irrigation (FI) were quantified. Field experiments were conducted in two growing seasons under the full irrigation treatment (FIT), limited irrigation treatments of 80% FIT and 60% FIT and rainfed treatment (RFT). The highest NUE was observed under limited irrigation in the order of 80% FIT > FIT ≥ 60% FIT in non‐traditional treatment‐1 (NT‐1) in both the CP and SDI methods. NUtE increased with irrigation amount. There were strong correlations between NUtE and grain yield regardless of irrigation method. ETa increased with N amount, and the slopes of these relationships varied substantially between irrigation and N levels and irrigation methods. PFPN increased with irrigation amount across the irrigation methods and N treatments. A higher PFPN was observed in the lowest total applied N plots and in‐season split N application treatments. The pooled data for the CP and SDI methods showed significantly higher PFPN (20.3%) than the FI method, whereas the PFPN values in the CP and SDI methods were equal.

Drip fertigation triggered by soil matric potential reduces residual soil nitrate content and improves maize nitrogen uptake and yield stability in an arid area

Effective water and fertilizer management is crucial for enhancing nitrogen (N) use efficiency and ensuring regional food security, especially in arid regions. Drip fertigation can synchronize water and fertilizer supply with crop demand, but its maximum benefits can only be achieved with appropriately designed and well-managed irrigation systems. In this study, we built on our previous work on optimizing the design of drip irrigation systems and evaluated the effect of drip fertigation regimes on soil nitrate nitrogen (NO3-N) supply, crop N uptake, yield, and yield stability. We conducted a five-year field experiment using drip fertigation to grow maize (Zea mays L.) in the Hetao Irrigation District, Northwest China, from 2016 to 2020. We implemented three water levels by controlling soil matric potential (SMP) threshold values [− 10 kPa (S1), − 30 kPa (S3), and − 50 kPa (S5)] under the same N fertilization rate (150 kg N ha−1 broadcast as basal fertilizer, 150 kg N ha−1 applied with drip fertigation). Our results indicated that soil NO3-N in 0–60 cm profile was typically distributed in the non-mulched zone at maturity. Compared with S5, S1 and S3 on average significantly decreased NO3-N accumulation in the 0–60 cm profile by 66% and 47%, and S1 and S3 significantly decreased NO3-N accumulation in the 60–120 cm profile by 31% and 30%. In addition, the S3 significantly decreased NO3-N accumulation in the 120–200 cm profile by 52% and 35% compared with S1 and S5. S3 significantly improved crop grain yield by 45%, sustainable yield index by 26%, N uptake by 28%, and N utilization efficiency by 11% compared with S5. In contrast, S3 decreased the irrigation amount by 40% compared with S1, with no significant differences in grain yield, yield stability, and N uptake in most years. We recommend using an SMP threshold value of − 30 kPa combined with a drip fertigation rate of 150 kg N ha−1 to reduce residual NO3-N and improve yield and yield stability in arid regions. Furthermore, we also recommend using drip fertigation with 208–253 mm irrigation water in wet years and > 253 mm in dry years (irrigation every four days from V6 to R3 stage), with 13.6 kg ha−1 N applied per irrigation (from VT to R3 stage) to facilitate farmer operations. Our research provides valuable technical guidance to promote a stable and sustainable agricultural production in arid regions.

Quantifying water productivity and nitrogen uptake of maize under water and nitrogen stress in arid Northwest China

Water and nitrogen (N) are critical determinants of crop water productivity (WP) and N uptake (Nuptake), and are also key factors in crop modelling. Through a two-year field experiment with three irrigation levels (full irrigation (W1), moderate water stress (W0.75), and severe water stress (W0.5)), three N application rates (150, 75, and 0 kg N ha−1, i.e., N150, N75, and N0) and three replications for each treatment in Northwest China, we quantified the effects of water and N stress on the growth, yield, and water and N use efficiency (WP and NUE) of hybrid seed maize (Zea mays L. cv. Tianruifeng). Furthermore, nonlinear dynamic water productivity (WP) models and water (ET)-based Nuptake models were developed. The results showed that water stress had a larger impact than N stress on the growth and yield of maize, with water stress reducing yield (Y), final aboveground biomass (B), and N uptake by 36.5%, 15.4%, and 25.7% on average, respectively, and N stress decreasing them by 18.7%, 12.3%, and 13.6%, respectively. Biomass-based water productivity (WPB-ET) and yield-based water productivity (WPY-ET) at the end of the growth period responded differently to water stress but similarly to N stress because of a higher decrease of harvest index (HI) under water stress than under N stress. Specifically, WPY-ET decreased significantly while WPB-ET kept relatively stable as water stress increased. The variation of the measured WP during the growth period presented a single peak trend. The Logistic, Sigmoid, and Linear models showed similar high accuracy for quantifying the relationship between evapotranspiration accumulation and biomass growth. However, the derived WP values from the nonlinear dynamic models were more in line with the single peak variation of the measured WP during the growth period, with the agreement index (d) improved from 0.21 to 0.65–0.75 in comparison to the Linear model. The developed ET-based N accumulation models can quantify N uptake through evapotranspiration. The results can contribute to improving the accuracy of crop modelling under drought stress conditions, and the design of irrigation and N management in arid and semi-arid regions.

Assessment of maize nitrogen uptake from PRISMA hyperspectral data through hybrid modelling

ABSTRACT The spaceborne imaging spectroscopy mission PRecursore IperSpettrale della Missione Applicativa (PRISMA), launched on 22 March 2019 by the Italian Space Agency, opens new opportunities in many scientific domains, including precision farming and sustainable agriculture. This new Earth Observation (EO) data stream requires new-generation approaches for the estimation of important biophysical crop variables (BVs). In this framework, this study evaluated a hybrid approach, combining the radiative transfer model PROSAIL-PRO and several machine learning (ML) regression algorithms, for the retrieval of canopy chlorophyll content (CCC) and canopy nitrogen content (CNC) from synthetic PRISMA data. PRISMA-like data were simulated from two images acquired by the airborne sensor HyPlant, during a campaign performed in Grosseto (Italy) in 2018. CCC and CNC estimations, assessed from the best performing ML algorithms, were used to define two relations with plant nitrogen uptake (PNU). CNC proved to be slightly more correlated to PNU than CCC (R 2 = 0.82 and R 2 = 0.80, respectively). The CNC-PNU model was then applied to actual PRISMA images acquired in 2020. The results showed that the estimated PNU values are within the expected ranges, and the temporal trends are compatible with plant phenology stages.

The Influence of Aerial Hyperspectral Image Processing Workflow on Nitrogen Uptake Prediction Accuracy in Maize

A meticulous image processing workflow is oftentimes required to derive quality image data from high-resolution, unmanned aerial systems. There are many subjective decisions to be made during image processing, but the effects of those decisions on prediction model accuracy have never been reported. This study introduced a framework for quantifying the effects of image processing methods on model accuracy. A demonstration of this framework was performed using high-resolution hyperspectral imagery (<10 cm pixel size) for predicting maize nitrogen uptake in the early to mid-vegetative developmental stages (V6–V14). Two supervised regression learning estimators (Lasso and partial least squares) were trained to make predictions from hyperspectral imagery. Data for this use case were collected from three experiments over two years (2018–2019) in southern Minnesota, USA (four site-years). The image processing steps that were evaluated include (i) reflectance conversion, (ii) cropping, (iii) spectral clipping, (iv) spectral smoothing, (v) binning, and (vi) segmentation. In total, 648 image processing workflow scenarios were evaluated, and results were analyzed to understand the influence of each image processing step on the cross-validated root mean squared error (RMSE) of the estimators. A sensitivity analysis revealed that the segmentation step was the most influential image processing step on the final estimator error. Across all workflow scenarios, the RMSE of predicted nitrogen uptake ranged from 14.3 to 19.8 kg ha−1 (relative RMSE ranged from 26.5% to 36.5%), a 38.5% increase in error from the lowest to the highest error workflow scenario. The framework introduced demonstrates the sensitivity and extent to which image processing affects prediction accuracy. It allows remote sensing analysts to improve model performance while providing data-driven justification to improve the reproducibility and objectivity of their work, similar to the benefits of hyperparameter tuning in machine learning applications.

Grain Yield and Nitrogen Uptake of Maize (Zea mays L.) as Affected by Soil Management Practices and Their Interaction on Cambisols and Chernozem

Although numerous factors contribute to wide yield gaps, low external inputs, particularly N, and poor cropping practices such as soil tillage and monocropping are among the major factors affecting low maize production. In view of this, field experiments were implemented on two sites with Cambisols and Chernozem soil types in two consecutive years to evaluate the impacts of different soil management practices on the grain yield and quality, nitrogen uptake, and selected soil properties. A three-factor experiment was arranged as a split-split plot arrangement randomized complete block design with three replications. The minimum tillage (MT) and conventional tillage (CT) were used as the main plot, haricot bean-maize rotation and maize monocropping were used as the subplot, and four levels of nitrogen fertilization (control, 20 t ha-1 compost, 46 kg N ha−1 + 10 t ha−1 compost, and 92 kg N ha−1) were used as the sub-subplot. Analysis of variance showed that soil management practices were significantly affecting grain yield, N-uptake, and soil properties. In sites, the conventional tillage and rotation system increased the grain yield and N-uptake in contrast to the minimum tillage and monocropping, respectively. Similarly, nitrogen evidently affected the grain yield, N-uptake, and selected soil properties. However, tillage methods differed in their effects on soil chemical properties; soil organic carbon and total nitrogen concentrations were improved through MT compared to CT. Grain yield was significantly associated with NDVI, grain N-content, and N-uptake. Therefore, a CT plus haricot bean-maize rotation system with the addition of solely 92 kg N ha−1 and integrated 46 kg N ha−1 + 10 t compost ha−1 could be recommended for Hawassa Zuria (Cambisols) and Meskan (Chernozem) districts, respectively. However, in order to ensure sustainable maize production in the investigated areas, an integrated N treatment with MT and a rotation system may be recommended, which could improve soil properties.

Growth, Nitrogen Uptake of Maize (Zea mays L.) and Soil Chemical Properties, and Responses to Compost and Nitrogen Rates and Their Mixture on Different Textured Soils: Pot Experiment

Integrated nutrient management, which primarily involves the combined application of organic and inorganic nutrient sources, is one of the simplest approaches to handle declining soil fertility challenges and increase crop productivity and production. Keeping in view this fact, a pot experiment was conducted to evaluate the effects of compost and inorganic nitrogen fertilizer and their mixture on soil properties, growth, and nitrogen uptake of maize on loam and clay textured soils at the Awada Agricultural Research Subcenter. Treatments comprised factorial combinations of five compost rates (0, 5, 10, 15, and 20 t·ha−1) and four rates of inorganic nitrogen fertilizer (0, 46, 92, and 138 kg·N·ha−1) laid out as a completely randomized design with three replications. Results showed that both the main and interaction effects of compost and mineral N fertilizer rates significantly affected the selected soil chemical properties and yield, and nitrogen concentration of maize. There were significant associations between plant parameters and soil nitrogen contents. The addition of 92 kg·ha−1·N + 10 t·ha−1 compost and 46 kg·ha−1·N + 10 t·ha−1 compost was the best treatments for loam and clay textured soils of the study areas, which improved shoot dry matter by 179.5 and 284.5%, compared to the unfertilized pot, respectively. From the results of this experiment, we concluded that the integrated application of compost and mineral nitrogen fertilizer enhanced soil chemical properties and thus improved nitrogen uptake and sustainable production of maize in the study areas.

Mixture of controlled-release and conventional urea fertilizer application changed soil aggregate stability, humic acid molecular composition, and maize nitrogen uptake

Controlled-release urea (CRU) fertilizer application has been shown to improve crop yield and nitrogen (N) use efficiency. However, its effects when mixed with conventional urea fertilizer on soil aggregate stability, humic acid (HA) molecular composition and crop N uptake remain unclear. Soil and plant samples were collected from a long-term (2008–2019) experiment on field maize (Zea mays L., ‘Zhengdan 958’) which included two types of fertilizers [conventional urea fertilizer (CUF), blended CUF with CRU fertilizer (CRF)], four N application rates (0, 150, 300 and 450 kg ha−1), each in three replicates. The results showed that at 300 kg N ha−1, compared to CUF treatment, the CRF treatment significantly improved soil aggregate characteristics [aggregate content with particle size larger than 0.25 mm (R0.25) by 9.6%, mean weight diameter by 19.8%, and geometric mean diameter by 21.7%]. CRF treatment also increased HA content by 5.5%, fulvic acid (FA) by 5.5%, lignin-like molecules by 0.94 times, and protein-like molecules by 3.69 times. At grain-filling stage, CRF treatments significantly increased the sum of soil NH4+-N and NO3−-N content by 23.3–24.5%, sap bleeding rate by 12.8–18.2% and N delivery rate through bleeding sap by 60.6–87.7% compared to CUF treatments at the same N application rate. At the same rate of N application, the CRF treatments significantly improved the average yield during three growing seasons by 9.4–14.0% in contrast with CUF treatments. The regression equations showed that the maximum yield was 8294 kg ha−1 for CUF at the application rate of 312 kg N ha−1 while it was 9890 kg ha−1 for CRF at the application rate of 286 kg N ha−1. We conclude that the long-term application of CRF changed the HA molecular structure, enhanced the water stable aggregates, improved crop N uptake, and increased economically viable maize yield.

Brassinosteroids modulate nitrogen physiological response and promote nitrogen uptake in maize (Zea mays L.)

Brassinosteroids (BRs) are steroid hormones that function in plant growth and development and response to environmental stresses and nutrient supplies. However, few studies have investigated the effect of BRs in modulating the physiological response to nitrogen (N) supply in maize. In the present study, BR signaling-deficient mutant zmbri1-RNAi lines and exogenous application of 2,4-epibrassinolide (eBL) were used to study the role of BRs in the regulation of physiological response in maize seedlings supplied with N. Exogenous application of eBL increased primary root length and plant biomass, but zmbri1 plants showed shorter primary roots and less plant biomass than wild-type plants under low N (LN) and normal N (NN) conditions. LN induced the expression of the BR signaling-associated genes ZmDWF4, ZmCPD, ZmDET2, and ZmBZR1 and the production of longer primary roots than NN. Knockdown of ZmBRI1 weakened the biological effects of LN-induced primary root elongation. eBL treatment increased N accumulation in shoots and roots of maize seedlings exposed to LN or NN treatment. Correspondingly, zmbri1 plants showed lower N accumulation in shoots and roots than wild-type plants. Along with reduced N accumulation, zmbri1 plants showed lower NO3− fluxes and 15NO3− uptake. The expression of nitrate transporter (NRT) genes (ZmNPF6.4, ZmNPF6.6, ZmNRT2.1, ZmNRT2.2) was lower in zmbri1 than in wild-type roots, but eBL treatments up-regulated the transcript expression of NRT genes. Thus, BRs modulated N physiological response and regulated the transcript expression of NRT genes to promote N uptake in maize.

Effects of arbuscular mycorrhizal fungi on maize nitrogen uptake strategy under different soil water conditions

Arbuscular mycorrhizal fungi (AMF) could influence plant abilities of total nitrogen (N) acquisition. Global changes have been influencing availabilities of different N forms and water resources in soil. However, it is uncertain whether and how AMF colonization affects plant uptake and preference of different N forms and how are they affected by soil water conditions. We conducted a pot experiment with Funneliformis mosseae (a common arbuscular mycorrhizal fungal species) colonized and non-colonized maize (Zea mays L.) growing at low and high water conditions, the growth medium contained much more nitrate (NO3−) than ammonium (NH4+). F. mosseae colonization and high water availability increased maize biomass and total N uptake. Enhanced water supply increased proportional contributions of NH4+ to colonized and non-colonized maize because high water conditions may increase NH4+ accessibility to maize. F. mosseae colonization weakened proportional contributions and preference of NH4+ in maize, indicating that AMF enable plants to prefer using the more abundant N form and develop more beneficial N uptake strategies considering that NO3− was more dominant than NH4+ in growth medium. Furthermore, maize NH4+ preference was decreased by F. mosseae colonization more under high than low water conditions. This demonstrated greater effects of AMF on regulating plant N uptake strategies in soils with greater water availability. This work revealed the regulation of AMF colonization on plant N uptake strategies under different soil water conditions. The findings enriched our knowledge of plant N use in the context of global changes.

Combined application of biochar with fertilizer promotes nitrogen uptake in maize by increasing nitrogen retention in soil

Combined application of biochar with fertilizers has been used to increase soil fertility and crop yield. However, the coupling mechanisms through which biochar improves crop yield at field scale and the time span over which biochar affects carbon and nitrogen transformation and crop yield are still little known. In this study, a long-term field trial (2013–2019) was performed in brown soil planting maize. Six treatments were designed: CK—control; NPK—application of chemical fertilizers; C1PK—low biochar without nitrogen fertilizer; C1NPK, C2NPK and C3NPK—biochar at 1.5, 3 and 6 t ha−1, respectively, combined with chemical fertilizers. Results showed that the δ15N value in the topsoil of 0–20 cm layer in the C3NPK treatment reached a peak of 291 ‰ at the third year (2018), and demonstrated a peak of 402 ‰ in the NPK treatment in the initial isotope trial in 2016. Synchronously, SOC was not affected until the third to fourth year after biochar addition, and resulted in a significant increase in total N of 2.4 kg N ha−1 in 2019 in C3NPK treatment. During the entire experiment, the 15N recovery rates of 74–80% were observed highest in the C2NPK and C3NPK treatments, resulting in an annual increase in yields significantly. The lowest subsoil δ15N values ranged from 66‰ to 107‰, and the 15N residual rate would take 70 years for a complete decay to 0.001% in the C3NPK. Our findings suggest that biochar compound fertilizers can increase C stability and N retention in soil and improve N uptake by maize, while the loss of N was minimized. Biochars, therefore, may have an important potential for improving the agroecosystem and ecological balance.Graphic abstract

Influence of Zeolite on Nitrogen Fractions, Nitrogen Use Efficiency and Nitrogen Uptake of Maize

Imbalanced use of fertilizers for agricultural production has now become a global concern. As a result, studies on how to use efficient methods to reduce nutrient applications at the same time increasing or maintaining crop yield, reducing nutrient losses and improving nutrient use efficiency are imperative. Accordingly, a pot study was conducted to evaluate whether zeolite application might improve selected soil properties, nitrogen use efficiency during maize cultivation. Among all treatments, irrespective of the nitrogen level, NUE (N recovery and agronomic use efficiency of N) showed an increasing trend with the increase of zeolite levels, nitrogen levels and their combination. The highest N recovery and agronomic NUE was obtained in N200Z7.5 (Nitrogen @ 200 kg ha-1 + Zeolite @ 7.5 t ha-1), was on par with N200Z5 (Nitrogen @ 200 kg ha-1 + Zeolite @ 5 t ha-1). N uptake by maize at harvest was highest in N200Z7.5 (Nitrogen @ 200 kg ha-1 + Zeolite @ 7.5 t ha-1).

Maize nitrogen uptake and productivity under reduced and conventional tillage

Reduced tillage (RT) systems have been promoted for crop production intensification in low potential areas through enhancement of fertiliser response of degraded soils and drought mitigation. A 3 year study was conducted from 2015/2016 to 2017/2018 growing seasons in sub-humid (650–1000 mm rainfall year−1) Zimbabwe to determine nitrogen (N) uptake and maize yield response to nitrogen fertilisation rate (0, 30, 60, 90 120 150, 180 k gha−1) under RT and conventional tillage (CT). The experimental design was a split plot, with the two tillage systems as main plot and seven N rates as the sub-plot treatments. Four sites were established in smallholder farmer fields with clayey soils (160–400 g clay kg−1; Chromic Luvisols and Rhodic Ferralsols) and sandy soils (40–100 g clay kg−1; Eutric Regosols). Results show that the study sites had rainfall deficits of 4–47% in the first and third growing seasons. Nitrogen uptake rates of 8–60 kg ha−1 resulted in fertiliser N recovery efficiencies of 5–40% which were two fold higher under RT than under CT system. Maize grain yields (0.3–11 t ha−1) were 33% higher under RT than CT and increased 1.88–2.72 fold under N fertilisation compared to the control. The mismatch between top dressed N and peak crop demand require precision fertilisation in the dry seasons. Agroecology based quadratic modelling revealed that maximum maize yields of 2–13 t ha−1 were obtainable at optimum N fertilisation rates that were lower under RT than CT. The study provided a robust starting point in the improvement of nitrogen fertiliser management for maize under reduced tillage and climate variability.

Nutrient uptake and productivity of four tropical cropping systems under biochar amendment

AbstractIntegrated measures including climate‐smart options have been proposed to improve crop production in sub‐Saharan Africa. However, there are limited studies exploiting biochar (BC) use under different cropping systems in the region. We evaluated nutrient uptake, grain and biomass yields, and economic viabilities of integrated use of BC under cereal‐ and legume‐based cropping systems in Ghana. The two‐factor field experiment was conducted in three consecutive cropping seasons and comprised soil amendments (BC, NPK fertilizers, 50% NPK + 50% BC, and control) and cropping systems (sole maize [Zea mays], maize intercropped with soybean [Glycine max (L.) Merr.], sole soybean and cowpea [Vigna unguiculata L.]). Generally, sole application of mineral fertilizers increased (p < .05) maize grain yield more than the 50% NPK+50% BC. Conversely, the 50% NPK + 50% BC generally produced similar yields (p > .05) of cowpea and soybean as the sole application of the 100% recommended NPK rates. For maize biomass yield, 50% NPK + 50% BC generally outperformed the sole NPK and sole BC treatments. Nutrient uptake in maize was higher in sole NPK and the integrated plots under sole cropping than in intercropping system. Nitrogen uptake of maize in 50% NPK + 50% BC was 12–22% higher in sole cropping than in intercropping system. The value/cost ratio under NPK was above the economic threshold (>2.0) under cropping systems. For 50% NPK + 50% BC, the economic threshold was only exceeded under intercropping cropping system, indicating a considerable intercropping benefits in integrated biochar and mineral fertilizer application.