Apparent Nitrogen Recovery Research Articles

Combined inorganic and organic fertilizers improved soil microbial biomass and nitrogen dynamics in Upper Eastern region of Kenya

Soil microbial biomass elements and mineralization processes are essential in replenishing soil nutrients. Yet, the effect of fertilization on the microbes is still not well-defined. This study aimed to determine the effect of integrated soil fertility inputs (inorganic and organic) on microbial biomass, carbon (MBC), nitrogen (MBN), phosphorus (MBP), nitrogen (N) mineralization, and N use efficiency in a field experiment. The treatments were: control (no fertility input), sole inorganic fertilizer, and different combinations of inorganic and organic inputs in a randomized block design. The results showed that Conventional tillage + maize residue + goat manure + Dolichos lablab intercrop (CT4); minimum tillage + maize residue + Tithonia diversifolia + goat manure (MT5); and minimum tillage + maize residue + goat manure + Dolichos lablab (MT4) intercrop increased microbial C, N, and P by 78 %, 48 %, and 41 %, respectively compared to control (CT0). Compared to CT0, N mineralization significantly varied (p < 0.0001) among the treatments at planting and on the 15th, 30th, 45th, and 60th days after planting during the 2020 short rains season. It also differed significantly (p = 0.0018, 0.0028, < 0.0001, and 0.0028,) on the 45th, 60th, 75th, 90th, and 105th days, respectively, relative to CT0 after planting during the 2021 long rains season. The CT4 had 5.11 and 52.80 kg N ha−1 higher apparent nitrogen recovery and partial factor productivity N, respectively. Similarly, MT4 greatly enhanced N apparent recovery efficiency by 57.5 % relative to CT0. Integrating fertility inputs improved soil biological fertility and mineralized N. Therefore, technologies that integrate organic inputs, either solely or with inorganic fertilizers, should be harnessed and promoted as medium and long-term technologies to advance soil biological fertility, and mineral N and N use efficiency in smallholder farmers.

Evaluation of urea loaded nanoclay biopolymer composites with Zn and P solubilizing microbes for nitrogen uptake and use efficiency in maize (Zea mays)-wheat (Triticum aestivum) cropping system

A field experiment was conducted during rainy (kharif) 2022 (July 2022–October 2022) and winter (rabi) 2022–23 (November 2022–March 2023) seasons at ICAR-Indian Agricultural Research Institute, New Delhi to evaluate a series of Zn and P solubilizing microbial culture enriched nanoclay biopolymer composite (NCBPC) loaded with nitrogenous fertilizer (urea) and the efficiency of the products for maize (Zea mays L.) and wheat (Triticum aestivum L.). Experiment consisted of 10 treatments, viz. T1, Control; T2, 100% N though urea; T3; T5; T7; and T9, 75% N as urea loaded NCBPC-A (prepared using acrylic acid + acrylamide + mango kernel flour) alone or along with P or Zn or P + Zn solubilizers; T4; T6; T8 and T10, 75% N as urea loaded NCBPC-B (prepared using acrylic acid + acrylamide + maize flour) alone or along with P or Zn or P + Zn solubilizers in a randomized block design (RBD) and replicated thrice. In both maize and wheat crop, highest grain (5.09 and 5.32 t/ha) and straw yield (6.56 and 7.45 t/ha), apparent N recovery (51.26 and 47.26%) and agronomic efficiency (12 and 13.3 kg grain yield obtained/kg N application) were obtained in treatment T10 followed by T9. In addition, total N uptake significantly enhanced by 20.1–28.4% in maize and 22.1–30.8% in wheat (T9 and T10); apparent nitrogen recovery (ANR) improved by 12.9–18.2 and 15.2–21.1% and agronomic efficiency (AE) triggered by 19.5–21.2 and 15.4–20.8% in maize and wheat crops respectively, under T9 and T10 treatments over standard urea fertilization (T2). Thus, the study concludes that, 25% N requirement could be cut down through application of 75% N (urea) loaded NCBPCs in conjunction with Zn or P or Zn + P solubilizing microbial culture as compared to sole urea application under maize-wheat cropping system.

Optimization of Urea Super Granule Boost up for the Efficiency of N and Improved the Potato Quality, Growth and Yield

Potato is the third most important food crop after wheat and rice in Bangladesh. To determine the suitable nitrogen source by observing the growth performance with a view to increasing the yield of potato, a research work was carried out at the Research Farm, Sher-e-Bangla Agricultural University, Dhaka during the period from November 2018 to March, 2019. The experiment consisted of eight treatments. The experiment was laid out with Randomized Complete Block Design with three replications. Experimental results showed that nitrogen sources had significant effect on plant height, number of effective stem hill-1, wt. of tuber (g hill-1), yield of tubers (kg plot-1), yield of tubers (t ha-1), tuber fleshy dry matter content, specific gravity, grading of tubers (% by number). Potato production increased significantly due to the application of Urea Super Granule (USG). The highest production was observed in T3 treatment. The application of T3 treatment showed the highest wt. of tuber hill-1 (57.53g hill-1), highest tuber yield (25.77 kg plot-1), highest tuber yield (29.45 t ha-1) than any other sources of nitrogen treatments. The mean apparent recovery of Nitrogen by tested variety BARI Alu 7 (Diamant) was obtained with the application of USG in other treatment (except control) but the nitrogen use efficiency was highest in T3 treatment. Findings revealed that application of USG showed the superiority over other sources of nitrogen to produce highest tuber yield of potato and for all cases lowest results were found in T1 treatment receiving no fertilizer (control).

Zinc-Coated Urea with Gelatin-Enhanced Zinc Biofortification, Apparent Nitrogen Recovery, and Ryegrass Production

Zinc-Coated Urea with Gelatin-Enhanced Zinc Biofortification, Apparent Nitrogen Recovery, and Ryegrass Production

Straw Residual Retention on Wheat Photosynthetic Characteristics, Utilization of Water and Nitrogen, and Reactive Nitrogen Losses

Straw residual retention is an emerging and promoted practice in rain-fed northwest China, but its effect on wheat photosynthetic characteristics, the utilization of water and nitrogen, and reactive nitrogen losses is poorly understood. A two-year consecutive field experiment was conducted to investigate the impacts of residual incorporation into soil and nitrogen application on wheat nitrogen and water utilization, yield and nitrogen losses during 2018–2020. The split-plot design of two tillage systems [conventional tillage (CT), and straw residue incorporated into soil (SR)] and three nitrogen rates [0 kg ha−1 (N0), 144 kg ha−1 (N144), 180 kg ha−1 (N180)] was implemented. Our results demonstrated that compared to CT, SR significantly influenced several key metrics. Compared with CT, SR increased the wheat photosynthetic rate (Pn), transpiration rate (Tr), leaf area index (LAI), leaf total chlorophyll (Chl-total), glutamine synthetase (GS) and nitrate reductase (NR) by an average of 5.38%, 12.75%, 8.21%, 5.79%, 16.21% and 20.08%, respectively (p &lt; 0.05). In addition, SR increased the wheat grain yield and nitrogen uptake accumulation (NUA), evapotranspiration (ET), precipitation storage efficiency (PSE), and mineral nitrogen residual after harvest (except for SR-N180 in 2019–2020), but decreased the apparent nitrogen recovery when compared with CT. However, there was an insignificant difference in the ammonia (NH3) volatilization and nitrous oxide (N2O) emissions of SR and CT. With an increase in the N-fertilization rate, the Pn and Tr, NH3 volatilization, N2O emission, mineral nitrogen residual (except for SR-N180 in 2019–2020), LAI, Chl-total (except for SR-N180 and CT-N180 in 2018–2019), GS, NR, grain yield, WUE, and NUA increased significantly; however, the ET, PSE, apparent nitrogen recovery (ANR), and nitrogen harvest index (NHI) decreased significantly. Furthermore, the differences between N144 and N180 in terms of the photosynthetic characteristics of wheat, the utilization of water and nitrogen, and yield were not significant. Overall, straw retention with N144 could be recommended as a resource-saving and environment-friendly management practice in a rain-fed winter wheat–fallow cropping system in northwest China.

Effect of Nitrogen Fertilizers Applied through Nano Clay Polymer Composites on Nitrogen Use Efficiency of Rice

Nitrogen (N) is an essential nutrient for crop growth. However, excessive nitrogen fertilizer application leads to environmental losses. In this study, an attempt was made to reduce the nitrogen losses by loading of urea and urea ammonium nitrate (UAN) into Nano clay polymer composites (NCPCs) to act as slow release N fertilizers. To achieve the objectives of the present study, five N fertilizer treatments (T1-control, T2- N applied through urea, T3- N applied through UAN, T4- N applied through NCPC loaded with urea and T5- N applied through NCPC loaded with UAN) were assessed using three rice genotypes namely IR-64, Nagina 22 and MTU 1010. Results of the greenhouse study indicated that the UAN loaded NCPC treatment was more effective in terms of increasing the grain yield, nitrogen uptake, agronomic use efficiency and apparent nitrogen recovery by 36.9%, 51.0%, 64.2%, and 92.0% over urea, respectively. Amongst the genotypes, MTU 1010 was recorded with highest gran yield followed by IR-64 and Nagina-22.

Optimization of Nitrogen Fertilizer Management in the Yellow River Irrigation Area Based on the Root Zone Water Quality Model

Strategic management of nitrogen fertilizers can not only mitigate agricultural nitrogen pollution but also significantly enhance crop yield and nitrogen use efficiency. This study was designed to determine the optimal nitrogen fertilizer management strategy for the Yellow River irrigation area. Leveraging two years of field data related to soil water nitrogen and summer maize growth indices, parameters for the Root Zone Water Quality Model 2 (RZWQM2) were calibrated and validated. Subsequently, various scenarios were generated to simulate the impacts of different nitrogen application rates and basal chasing ratios on summer maize yield, nitrogen agronomic efficiency, nitrogen physiological efficiency, and nitrogen apparent recovery rate. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was employed for a comprehensive evaluation. RZWQM2 can effectively simulate the dynamic changes in soil moisture and nitrogen in the Yellow River irrigation area, and the results indicated that the mean relative error (MRE) between the simulated and observed values varied from 5.77% to 14.09%, and 4.36% to 33.01%, while the root mean square error (RMSE) ranged from 0.016 to 0.037 cm3/cm3, and 0.111 to 1.995 mg/kg. The normalized root mean square error (NRMSE) varied between 6.20% to 14.42% and 5.24% to 17.84%, respectively. The results validate the model’s effectiveness in simulating summer maize yields and nitrogen metrics under varying nitrogen fertilizer management practices. A nitrogen application rate of 180–200 kg/hm2 (expressed in terms of pure nitrogen) in the Yellow River irrigation area could adequately meet the requirements for summer maize production. The recommended nitrogen fertilizer management strategy in the Yellow River irrigation area involves applying 200 kg/hm2 of nitrogen in a 1:2:1 ratio during the sowing, trumpeting, and anthesis stages.

Under a Tropical Climate and in Sandy Soils, Bat Guano Mineralises Very Quickly, Behaving More like a Mineral Fertiliser than a Conventional Farmyard Manure

In sub-Saharan Africa, soil fertility management must rely on local fertiliser resources since most smallholder farmers do not have access to industrial fertilisers. In Vilankulo, Mozambique, farmers have access to bat guano and biochar, albeit in small amounts, which makes it even more necessary to manage them correctly to maximise crop productivity. This study was carried out with irrigated maize (Zea mays L.) in a haplic Lixisol during the 2017/2018 and 2019 growing seasons. Nine treatments were established consisting of the application of 5 (G5) and 10 (G10) t ha−1 of guano at sowing, 5 (B5) and 10 (B10) t ha−1 of biochar at sowing, 5 [G5(-1)] and 10 [G10(-1)] t ha−1 of guano one month before sowing, 1 and 4 (B1G4) and 2 and 8 (B2G8) t ha−1 of biochar and guano, respectively, at sowing and an unfertilised control (C). Treatments G10 and B2G8 led to the highest maize yields (3.77 and 2.68 t ha−1 in 2018 and 5.05 and 5.17 t ha−1 in 2019, respectively), and were statistically higher than those of the control (1.35 and 1.63 kg ha−1, respectively). Apparent nitrogen recovery from bat guano was close to 100%, showing almost complete mineralisation during the maize growing season, due to its low carbon/nitrogen ratio and very favourable environmental conditions for mineralisation. Due to the fast release of nutrients, bringing forward the application of the organic amendment before sowing is not recommended, since it reduces nutrient use efficiency. Biochar did not significantly influence maize grain yield or contribute significantly to plant nutrition. To take advantage of its potential effect on some soil properties, its use in combination with other materials of greater fertilising value is recommended.

Organic fertilizer substitutions maintain maize yield and mitigate ammonia emissions but increase nitrous oxide emissions.

Organic fertilizer can improve soil structure and enhance the nutrient content in soil and is beneficial to sustainable agricultural development. However, the influence of organic fertilizer substitutions on NH3 and N2O emissions from farmland is unclear. Thus, we set up an organic substitution field experiment in Northeast China. The experiment included six treatments: single application of chemical fertilizers (NPK: 250kg N ha-1); NO10, 10% reduction in chemical nitrogen fertilizers (225kg N ha-1) + chicken manure (25kg N ha-1); NO20, 20% reduction in chemical nitrogen fertilizers (200kg N ha-1) + chicken manure (50kg N ha-1); NO30, 30% reduction in chemical nitrogen fertilizers (175kg N ha-1) + chicken manure (75kg N ha-1); NO40, 40% reduction in chemical nitrogen fertilizers (150kg N ha-1) + chicken manure (100kg N ha-1); and no-nitrogen fertilizer (CK). This experiment investigated the effects of partial substitution of chemical nitrogen fertilizer with organic fertilizer on NH3 and N2O emissions and nitrogen use efficiency in a maize field. The results showed that, compared with chemical N, organic fertilizer mitigated NH3 volatilization but promoted the soil N2O total emissions during the whole growth stage. NH3 cumulative volatilization decreased with the increase in the substitution rate of organic fertilizer. Compared with the NPK treatment, the cumulative volatilization of NH3 in the NO30 and NO40 treatments decreased by 15.24 and 17.92%, respectively. The NO40 treatment had the highest N2O emission in the whole growth stage, and the N2O emission of the NO40 treatment increased by 10.72% compared to the NPK treatment. Moreover, the yield, partial factor productivity (PFP), nitrogen harvest index (NHI), and apparent nitrogen recovery efficiency (NRE) of NO30 treatment were the highest of all treatments, and the yields, PFP, plant N accumulation, grain N accumulation, and the cumulative emissions of NH3 and N2O were similar to N20 treatment. In conclusion, nitrogen fertilizer use efficiency was enhanced, decreasing environmental pollution from livestock under organic fertilizer substitution conditions. We suggested 20% or 30% substitution rates of organic fertilizer were proper.

Effect of enriched biochar based fertilizers on growth, yield and nitrogen use efficiency in direct-seeded rice (Oryza sativa)

A field experiment was conducted at Norman E. Borlaug Crop Research Centre, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand during kharif (rainy) 2018 to assess effect of enriched biochar (EB) based fertilizers on crop growth, productivity and nutrients use efficiency in direct seeded rice (DSR). Enriched biochar based fertilizers i.e. Enriched biochar-1 (EB-1), Enriched biochar-2 (EB-2), Urea enriched biochar-1 (UEB-1) and Urea enriched biochar-1(UEB-2) were prepared and characterized at IFS laboratory, GBPUA&amp;T, Pantnagar.The experiment was laid out in randomized block design with eight treatments i.e. 100% Recommended dose of fertilizer (RDF) through conventional fertilizers, 75, 100 and 125% RDF through enriched biochar based fertilizers EB-1+UEB-1 and EB-2+UEB-2 and no fertilizer application as control replicated thrice. Highest growth, yield parameters and yield of DSR were recorded under application of EB-2+UEB-2 at 125% fertility level. Application of EB-2+UEB-2 at 100% fertility level also gave at par yield with its application at 125% fertility level and significantly higher yield (13.5%) as compared to application of conventional fertilizers at similar fertility level. Application of both the EB fertilizers at 75% fertility level resulted in at par yield with application of 100% fertility level through conventional fertilizers. Nitrogen uptake by grain and straw were significantly higher under application of EB-2+UEB-2 at 125% fertility level. However, among these EB fertilizers, application of 100% RDF through EB-2+UEB-2 resulted in 30.70% and 29.50% more agronomic efficiency (AE) and apparent nitrogen recovery (ANR), respectively as compared to application of conventional fertilizers.

Role of zinc-coated urea fertilizers in improving nitrogen use efficiency, soil nutritional status, and nutrient use efficiency of test crops

The rise in global population, urbanization, and desertification pushes the farming community toward intensive cropping to meet the augmented food demands with consequent exhaustion of soil’s nutritional status and fertility. In recent times, environmental pollution and cost of crop production have been enhanced due to excessive and inefficient use of nitrogenous fertilizers. As an abatement strategy, seven different coated urea fertilizers, namely, gelatin-coated (G), zinc oxide with gelatin-coated (ZnOG), zinc oxide-coated (ZnO), sonicated zinc oxide-coated (ZnO-Son), zinc oxide with molasses-coated (ZnOM), zinc sulfate with molasses-coated (ZnSM), and zinc sulfate-coated (ZnS) were prepared in a fluidized bed coater. The coated samples were characterized through XRD, SEM, and FTIR techniques, while a crushing strength test was carried out to assess the impact of inventory operations on physical integrity of coated prills. Pot tests with ryegrass (Lolium perenne) as a test crop were carried out to evaluate the effect of coated urea fertilizers on yield and nitrogen (N) and zinc uptake in order to enhance nitrogen use efficiency and reduce pollution. Our results suggest that the affinity between urea surface and coating materials was of physical nature. All zinc oxide- or gelatin-coated treatments significantly increased the dry matter yield, nitrogen uptake, apparent nitrogen recovery (ANR), zinc uptake, and apparent zinc recovery (AZnR). ZnOG was proved to be the best sample in terms of balancing soil chemical properties with improved soil nutrition and producing best with plant yield (94% higher than UC), N uptake (75% higher than UC), Zn uptake (450% higher than UC), and nitrogen use efficiency (48 vs. 23% for UC). Our results suggest that the use of such coated fertilizers can lead to improve yields, nutritional values of crops, and overall agro-ecological scenario.

Effects of combined nitrification inhibitors on soil nitrification, maize yield and nitrogen use efficiency in three agricultural soils

Application of nitrification inhibitors (NIs) with nitrogen (N) fertilizer is one of the most efficient ways to improve nitrogen use efficiency (NUE). To fully understand the efficiency of NIs with N fertilizer on soil nitrification, yield and NUE of maize (Zea mays L.), an outdoor pot experiment with different NIs in three soils with different pH was conducted. Five treatments were established: no fertilizer (Control); ammonium sulfate (AS); ammonium sulfate + 3, 4-dimethyl-pyrazolate phosphate (DMPP) (AD); ammonium sulfate + nitrogen protectant (N-GD) (AN); ammonium sulfate + 3, 4-dimethyl-pyrazolate phosphate + nitrogen protectant (ADN). The results showed that NIs treatments (AD, AN and ADN) significantly reduced soil nitrification in the brown and red soil, especially in AD and ADN, which decreased apparent nitrification rate by 28% - 44% (P < 0.05). All NIs treatments significantly increased yield and NUE of maize in three soils, especially ADN in the cinnamon soil and AD in the red soil were more efficiency, which significantly increased maize yield and apparent nitrogen recovery by 5.07 and 6.81 times, 4.39 and 8.16 times, respectively. No significant difference on maize yield was found in the brown soil, but AN significantly increased apparent nitrogen recovery by 70%. Given that the effect of NIs on both soil nitrification and NUE of maize, DMPP+N-GD was more efficient in the cinnamon soil, while N-GD and DMPP was the most efficiency in the brown and red soil, respectively. In addition, soil pH and soil organic matter play important role in the efficiency of NIs.

Cocoa Clones Reveal Variation in Plant Biomass, Root Nitrogen Uptake, and Apparent Nitrogen Recovery at the Seedling Stage

We aimed to investigate variation in growth, biomass, macro-nutrient uptake, and nitrogen (N) use efficiency indices of cocoa (Theobroma cocoa L.) scion clones under two different nitrogen conditions. Ten clones were top-grafted onto 4-month-old rootstocks clone MCC 02. Each seedling received either 0 or 4.6 g of nitrogen applied as urea fertilizer. The design was arranged as a two-factor experiment with four replicates in a factorial randomized block design. We measured stem diameter, biomass, nutrient concentration, and calculated nutrient uptake, nitrogen use efficiency (NUE), agronomic efficiency (AE), apparent nitrogen recovery (ANR), and physiological efficiency (PE). We found that clones significantly affected stem diameter and shoot biomass of both rootstocks and scions. Clones differed in root magnesium (Mg) and shoot calcium (Ca) concentration, root N, and shoot Mg uptake. Furthermore, a significant clone effect was observed on ANR, with local clones showing higher ANR than introduced clones. Nitrogen application significantly improved stem diameter and biomass. Compared to unfertilized plants, a significantly higher N concentration was observed in roots, resulting in higher N uptake in both roots and shoots. Nitrogen application increased shoot Ca concentration and uptake but decreased shoot phosphorus (P) and Mg concentrations. Our results suggest genotypic variability in nitrogen uptake efficiency in clonal cocoa. Clones with high nitrogen uptake efficiency are valuable genetic resources for breeding cocoa clones that efficiently use available N and, therefore, grow better under N-deficient conditions.

Chemically and biologically activated biochars slow down urea hydrolysis and improve nitrogen use efficiency

Biochar is considered as a potential technology to enhance chemical fertilizer use efficiency through intensification of the interactions between nutrients and the functional groups on biochar surfaces. However, little is known on how application of activated biochars mixed with urea would influence nitrogen mineralization and crop performance in rice paddy fields. Here, a fresh sawdust biochar (FBC) (~400°C) was activated chemically with 15% H 2 O 2 and biologically with a nutrient solution mixed with a soil inoculum to obtain a chemically (CBC) and a biologically (BBC) activated biochar, respectively. The chemical and surface properties of these biochars were evaluated by spectroscopic methods (FTIR and 13 C-NMR) and by potentiometric charge determination. The N retention capacity of biochars and their interaction with the hydrolysis of urea were examined in a laboratory-based incubation. Additionally, a field trial was carried out in a paddy rice plot with these biochars after mixing at a ratio of 1:1 with or without urea. Our results showed that both activated biochars increased negative surface functional groups and negative charges after the activation process, especially in the case of CBC which was more effective than BBC. Both activated biochars contributed to a significant reduction in urea-biochar suspension pH while increasing N retention in a batch incubation. Despite the enhanced surface properties of the activated biochars, a similar increase in biomass and grain yield was observed for the three biochars in the field experiment. Similarly, apparent nitrogen recovery efficiency and agronomic efficiency were significantly higher in the three biochars than in control. Altogether, the results indicate that the application of urea mixed with biochar could enhance crop performance, especially in the case of activated biochars that would also enhance N retention in the soil preventing eventual N losses.

Evaluating combined effect of different coated urea with PGPR on yield and nitrogen use efficiency in lowland rice by regression model and principal component analysis approach

Nitrogen (N) loss is a key problem in rice fields, which results in low nitrogen use efficiency (NUE) of applied N and could be a major limitation from economic and environmental perspectives. In order to improve the NUE, use of slow or controlled released N fertilizers could be a potential alternative to the conventional N inputs. With this objective to evaluate the effect of different slow-release fertilizers on NUE and grain yield of rice, a pot experiment was conducted during kharif 2017 at Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University Varanasi. The experiment comprised thirteen treatments including control, Polymer (PCU) and Neem coated urea (NCU) and their combination with Farm yard manure (FYM) and Plant growth promoting rhizobacteria (PGPR). The combined application of PCU, NCU, FYM and PGPR in treatment T12 provided highest grain yield 47.98 gpot−1and followed by T8 46.60 gpot−1. The result showed that, compared with the PCU treatment T2 (PCU100 Split), the Agronomic efficiency (AE) and Apparent nitrogen recovery efficiency (ANR%) of the mixed doses of coated urea treatment T12 (PCU50 NCU50 FYM10 PGPR Basal) increased by 20.38% and 28.48% respectively. Therefore, application of FYM and PGPR with coated urea improved rice yield, nutrient uptake and their use efficiency and potentially recommended in eastern plain of the Indo-Gangetic Plain for the sustainable production of rice crop.

Clonal differences in nitrogen use efficiency and macro-nutrient uptake in young clonal cocoa (Theobroma cacao L.) seedlings from Indonesia

Nitrogen (N) is one of the most required nutrients in cocoa production. Unlike in many other crops, there is limited knowledge on genotypic variation in nitrogen use efficiency (NUE) in clonal cocoa. We therefore evaluated the effect of nitrogen application on cocoa NUE in 10 clonal cocoa scions that were top-grafted on 4-month old rootstock seedlings of cocoa clone MCC 02. Grafted seedlings received either 0 or 2.3 g/plant of N at the beginning of the experiment, which lasted for five months and was arranged in a nursery of the Indonesian Coffee and Cocoa Research Institute (ICCRI) in Jember, Indonesia. A factorial randomized block design was used with four replications. We found that clones significantly affected rootstock stem diameter and dry biomass both in roots and shoots. Nitrogen application decreased rootstock stem diameter and root biomass but increased shoot-root ratio. Following the N application, we observed significantly higher N concentration and uptake both in roots and shoots. This higher N concentration and uptake contributed to significantly lower NUE in both roots and shoots. We did not observe clonal differences in N concentration, uptake, NUE in either roots or shoots and ANR (Apparent Nitrogen Recovery). Nitrogen application influenced P, K, Mg, and Ca uptake in both roots and shoots. There was a clonal effect on P, K and Mg uptake and on P and Mg use efficiency in both roots and shoots. This implies that the studied clones vary in their P and Mg nutrient use efficiency but not in NUE.

Effects of Combined Nitrification Inhibitors on Nitrogen Transformation, Maize Yield and Nitrogen Uptake in Two Different Soils

ABSTRACT Nitrification inhibitors (NIs) affect nitrogen (N) cycle and crop yield, but how the combinations of NIs influence N transformation and maize yield remains unclear. An outdoor pot experiment was performed to explore the effect of three NIs (nitrapyrin (CP), 3, 4-dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD)) and their combinations on mineral N transformation, yield and N use efficiency (NUE) of maize in a brown soil and a cinnamon soil from northeast China. Higher yield and NUE were obtained in the brown soil than that in the cinnamon soil. All treatments with NIs significantly increased NH4+-N content, grain yield and NUE in both soils, especially for NIs combination (DMPP + DCD in the brown soil and CP + DCD in the cinnamon soil). These two treatments significantly increased yield and apparent nitrogen recovery by 1.84 and 2.31 times, 10.24 and 6.39 times, respectively, compared with N fertilizer treatment. They also showed lower apparent nitrification rates (17.2% and 53.7%, respectively) compared with single NIs treatments. Considering both the inorganic N supply and agronomic effect of NIs, DMPP + DCD and CP + DCD are the best strategies for the application of NIs in the brown soil and cinnamon soil.

Sulfur fertilization strategy affects grass yield, nitrogen uptake, and nitrate leaching: A field lysimeter study#

AbstractBackgroundGlobally and at the European Union level there are mounting concerns regarding nitrogen (N) losses from agricultural systems and pressure to reduce N losses to water and air. Suboptimal plant sulfur (S) availability can reduce plant N efficiency and thereby increase N loss potential. Climate change action demands lower sulfur dioxide emissions thus S deposition levels are at an all‐time low.AimsThe objectives of the current study were to (1) determine the potential for adequate S nutrition to increase grassland yield and N efficiency, (2) determine if alleviating S deficiency reduces nitrate leaching, and (3) evaluate a number of strategies for applying S including the use of cattle slurry.MethodsThis work was completed using a free‐draining sandy loam grassland lysimeter facility. There were six treatments using calcium ammonium nitrate (CAN), CAN + calcium sulfate (CAN+S), ammonium sulfate + CAN (AS+CAN), and slurry (Slurry+CAN and Slurry+CAN+S, respectively) to deliver S strategies. The yield, plant N and S uptake, and nitrate and sulfate leachate were measured to compare treatments.ResultsApplication of mineral S fertilizer increased yields significantly (up to 2,907 kg ha–1) and increased apparent fertilizer nitrogen recovery from 39% to 47–49%. Alleviating S deficiency also significantly decreased nitrate leaching to levels not differing significantly from the control. There was a reduction of 46% in nitrate leaching with the addition of mineral S (CAN+S and AS+CAN) compared to N only. The nitrate concentration standard for drinking water was not breached for treatments that included S (6.6–11 mg NO3–‐N L–1), whereas it was breached for those without S (23–40 mg NO3–‐N L–1). The S applied in the slurry treatment was not adequate (9 kg S ha–1) to meet plant requirements.ConclusionThis study provides evidence that optimization of S nutrition has the potential to deliver large agronomic and environmental benefits along with potential as a nitrate leaching migration strategy on S‐deficient soils.

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.

Influence of organics, inorganic and biofertilizers on growth, quality, yield, soil and plant nutrient status of marigold (Tagetes erecta L.) cv. Pusa Narangi Gainda

Organics, inorganics, and biofertilizers stimulate the growth, quality, yield, nutrient uptake, efficiency, and apparent nutrient recovery in marigold. A field trial was conducted for two consecutive years 2016/17 and 2017/18 during Fall to assess the influence of nutrients applied on growth, quality, yield, soil, and plant nutrient status of marigold. Azotobacter + vermicompost + 50% RDF responded highest plant height (76.91 cm) and increased phosphorus availability in soil at harvest (42.56 kg ha−1). However, increased number of secondary branches (22.35), leaf area (62.84cm2), E-W plant spread (49.80 cm), flower duration (103.36 days), number of flowers per plant (30.50), flower yield (234.75q ha−1), seed yield (5.87q ha−1), nitrogen, phosphorus, potassium uptake in flower (80.70 kg ha−1, 13.83 kg ha−1, and 73.02 kg ha−1), potassium use efficiency of plant (347.78 kg ha−1), apparent phosphorus and potassium recovery (16.95% and 93.97%) and postharvest available phosphorus of the soil (33.60 kg ha−1) were associated with Azospirillum + Azotobacter + vermicompost + 50% RDF. Azospirillum + Azotobacter + FYM + 50% RDF had shown maximum flower diameter (60.25 mm), carotenoid content in dry petals (11.37mg100g−1). Moreover, potassium uptake in stem (5.64 kg ha−1), nitrogen uptake efficiency (0.78%), phosphorus uptake efficiency (0.26%), nitrogen use efficiency (234.77 kg ha−1), phosphorus use efficiency (440.20 kg ha−1) and apparent nitrogen recovery (51.12%) was recorded to be highest in the treatment Azospirillum + Azotobacter + 50% RD N and P + 100% RD K. The study shows the great potential of organics and biofertilizers that could be used for integrated nutrient management in marigold.