Nitrogen Requirements Research Articles

Maize nutrient yield response and requirement in the maize belt of Nigeria

Absence of site-specific nutrient recommendation and high spatial variability of soil fertility are major factors affecting maize response to applied nutrients in Nigeria. In this study, we assessed maize response to applied nutrients and nutrient use efficiency in different management zones (MZs), for designing site-specific nutrient management recommendations for maize in the maize belt of Nigeria. The maize belt in Nigeria was earlier delineated into four MZsMZs (MZ1 to MZ4) based on soil properties. In the current study, data from two different trials, nutrient omission trials (N = 293) and fertilizer response trial (N = 705), conducted in the years 2015–2017, were extracted for MZ1 to MZ3; to analyze maize yield responses to application of N, P and K, and secondary and micro-nutrients. Maize yield response to K application was only positive in MZ1. Responses to N and P application were positive for all MZs. However, the magnitude of maize response to P varied between the MZs, indicating a differentiation in the degree to which P is limiting maize production in the study area. Average nitrogen requirement was higher for MZ3 (138 kg ha−1), than for MZ2 and MZ1 (121 and 83 kg ha−1, respectively). Average P requirement was higher for MZ3 (45 kg ha−1) than for the other zones. Potassium requirement was 26% and 28% higher in MZ2 and MZ3 compared with MZ1 (∼15 kg ha−1). The use of the specific nutrient rates for the MZs may reduce risks and uncertainties in crop production. The delineated MZs of the maize belt of Nigeria that incorporates spatial variability in soil fertility conditions are useful for nutrient management for larger areas.

Precrops and N-fertilizer impacts on soybean performance in tropical regions of Brazil

Precrops have different growth patterns, nitrogen (N) requirements, and production of residues varying in amounts and quality that may affect the N-clycling and the soybean (Glycine max L. Merrill) cropped in succession. This study aimed to evaluate the effect of precrops and N fertilization on soybean performance. An experiment was conducted in Londrina, Paraná State, Brazil, with six precrops treatments: fallow, ruzigrass (Urochloa ruziziensis), showy rattlebox (Crotalaria spectabilis), corn (Zea mays) without or with 80 kg ha−1 of N at topdressing as urea, and wheat (Triticum aestivum). Subplots consisted of two levels of N fertilization at soybean sowing: 0 and 30 kg ha−1 of N as ammonium nitrate at sowing. Urochloa ruziziensis as precrops increased the soybean yield (5,171 kg ha-1) when compared with corn (4,346 kg ha-1) and fallow (4,467 kg ha-1). In 2016/17, N fertilization of soybean with 30 kg ha−1 of N at sowing, although increasing the initial plant growth (745 kg ha-1 with vs. 662 kg ha-1 without), impairs nodulation (100 mg pl-1 with vs. 130 g pl-1 without) and does not increase grain yield. Oil and protein concentrations in soybean grains are not influenced by precrops and N fertilization at sowing. We found that the use Urochloa ruziziensis as cover crop in soybean precrops is a good recommendation option in tropical regions of Brazil, because increasing the yield of soybean grown in succession. N fertilization at in soybean sowing it should not be recommended even in the presence of a large amount of straw.

Влияние листовой подкормки на качество зерна озимой пшеницы в типичных сероземах с орошаемыми условиями

Abstract. The problem of improving the quality of winter wheat grain is urgent and at the same time relatively unresolved. In recent years, the yield of winter wheat on irrigated lands in many farms of the country is 50 cwt/ha and more. Depending on the type and variety of wheat, the protein content of the grains is 11–20% and is used for various purposes. If the protein content of wheat grains is up to 11–13%, it is used in the preparation of animal feed, up to 14–15% — bread and 17–18% — pasta. Most of the grains of winter soft wheat grown on irrigated lands of the country with a yield of 70–80 cwt/ha and above are used in the manufacture of bread and bakery products. At the same time, the quality of grain remains low, the protein content of the grain is up to 10–12%, the amount of crude gluten in it is in the range of 19–25%. The amount of this protein in the grain of winter wheat is much lower than the established norm, and the effectiveness of mineral fertilizers with foliar fertilization increases sharply, increasing the resistance of plants to sucking pests. The technological properties of the grain are dramatically improved, i. e. the protein content increases by 1.5–2.1%, gluten by 3.1–4.9%. Vitreous, its strength and bread volume increase. Nitrogen requirements of winter wheat are high throughout the growing season. In a wheat plant, 75–80% of nitrogen accumulates in the leaves and stems of the plant until the germination period. It is from this accumulated nitrogen that the bulk of the protein in the grain is formed. When the yield is high (65–70 cwt/ha), the amount of nitrogen accumulated in the leaves and stems of the plant does not ensure a sufficient amount of protein in the grain. In particular, nitrogen deficiency is observed in the formation of yield elements in winter wheat, i. e. during the period of development, flowering, flowering and milk ripening. For example, germination causes a number of difficulties in feeding through the soil due to overgrowth of the plant during flowering, low rainfall, or lack of water. On this reason, when winter wheat is harvested, there is a lack of nitrogen in the soil, which is easily absorbed by the plant. This in turn has a negative impact on wheat grain yield and quality.

Synthetic Biology Tool Development Advances Predictable Gene Expression in the Metabolically Versatile Soil Bacterium Rhodopseudomonas palustris.

Harnessing the unique biochemical capabilities of non-model microorganisms would expand the array of biomanufacturing substrates, process conditions, and products. There are non-model microorganisms that fix nitrogen and carbon dioxide, derive energy from light, catabolize methane and lignin-derived aromatics, are tolerant to physiochemical stresses and harsh environmental conditions, store lipids in large quantities, and produce hydrogen. Model microorganisms often only break down simple sugars and require low stress conditions, but they have been engineered for the sustainable manufacture of numerous products, such as fragrances, pharmaceuticals, cosmetics, surfactants, and specialty chemicals, often by using tools from synthetic biology. Transferring complex pathways has proven to be exceedingly difficult, as the cofactors, cellular conditions, and energy sources necessary for this pathway to function may not be present in the host organism. Utilization of unique biochemical capabilities could also be achieved by engineering the host; although, synthetic biology tools developed for model microbes often do not perform as designed in other microorganisms. The metabolically versatile Rhodopseudomonas palustris CGA009, a purple non-sulfur bacterium, catabolizes aromatic compounds derived from lignin in both aerobic and anaerobic conditions and can use light, inorganic, and organic compounds for its source of energy. R. palustris utilizes three nitrogenase isozymes to fulfill its nitrogen requirements while also generating hydrogen. Furthermore, the bacterium produces two forms of RuBisCo in response to carbon dioxide/bicarbonate availability. While this potential chassis harbors many beneficial traits, stable heterologous gene expression has been problematic due to its intrinsic resistance to many antibiotics and the lack of synthetic biology parts investigated in this microbe. To address these problems, we have characterized gene expression and plasmid maintenance for different selection markers, started a synthetic biology toolbox specifically for the photosynthetic R. palustris, including origins of replication, fluorescent reporters, terminators, and 5′ untranslated regions, and employed the microbe’s endogenous plasmid for exogenous protein production. This work provides essential synthetic biology tools for engineering R. palustris’ many unique biochemical processes and has helped define the principles for expressing heterologous genes in this promising microbe through a methodology that could be applied to other non-model microorganisms.

Tuber Yield and Physiological Characteristics of Potato Under Irrigation and Fertilizer Application

ABSTRACT The effects of water availability in the soil and fertilizer application often strongly affect crop growth. Tuber dry matter yield and physiological characteristics of potato (Solanum tuberosum L.) were investigated under different irrigation regimes (S1, full irrigation, 100% of water requirement; S2, 75% of water requirement; and S3, 50% of water requirement). Nitrogen treatments were four amounts of urea (N1, providing 100% of N requirement; N2, 66% of N requirement; and N3, 33% of N requirement, and N4, 0 kg N/ha. Drought stress with 50% of the water requirement and limiting nitrogen fertilizer application suppressed the number and weights of tubers per plant. The yield of marketable tubers in S1 and S2 treatments was not significantly different. Treatments N1, N2, and N3 increased the yield of marketable tubers by 37, 33 and 12%, respectively, compared to N4. Drought stress (S3) increased the percentage of dry matter, but nitrogen fertilization did not cause a significant change. Drought stress (S3) increased the amount of soluble sugars in tubers and proline in leaves; however, the amounts of soluble sugars and proline were unchanged by increased nitrogen fertilization. Full irrigation and meeting of nitrogen requirements of potatoes led to high chlorophyll concentrations in leaves. Under drought stress (S3) and increasing nitrogen, the starch content of tubers was suppressed. The amount of nitrate in the tubers was not affected by irrigation treatments, but was raised by increasing nitrogen fertilization. Irrigation of 75% or more combined with fertilizer application of 66%, was an appropriate treatment for potato production.

Effects of soil biotic and abiotic properties on the growth and mycorrhization of Cedrus atlantica Manetti cedars

Cedrus atlantica Manetti is an emblematic species of great ecological, economic and social value. However, its weak root architecture seriously compromises (re)afforestation and regeneration of the species. Although it is known that mycorrhization is beneficial to cedars growing in unfavourable conditions, our knowledge on the mycorrhization of cedar seedlings is remains patchy. These difficulties show a need to study the interactions between the roots and the soil biotic and abiotic factors and to seek solutions to promote the mycorrhization of cedar seedlings. For this purpose, we studied the responses of cedar seedlings to the physico-chemical, textural, hydromechanical and microbiological factors of the soil and mycorrhization success in juvenile cedars. The response of C. atlantica seedlings to the textural and physico-chemical properties of soils in cedar woods shows that they are highly dependent on organic carbon, nitrogen and phosphorus contents and on the soil's granulometry. These factors stimulate the growth of secondary roots in some soils while in others, they cause seedling growth to predominate. The provenances of C. atlantica show a high nitrogen requirement and different preferences for nitrogen forms. Variations in the cotyledons also reveal different patterns of adaptation to nitrogen nutrition. The hydromechanical properties of the culture medium profoundly affect C. atlantica seedlings, so that in extreme cases, they either over-stimulate the elongation of unbranched main roots or completely inhibit their elongation, producing a great many reduced lateral roots. On the anatomical scale, these responses are more apparent around the cortex. Interactions with the native soil microflora have a determining effect on the growth of C. atlantica seedlings, since the microbial composition of the soil can stimulate growth and decrease the density of roots. The nutrient depletion of 6 soils allowed the trapping of 15 species of ectomycorrhizal fungi of young C. atlantica seedlings. This indicates the crucial importance of this new range of mycorrhizal fungi, characterized for the first time in C. atlantica seedlings, especially for work aiming to improve the health status of cedar seedlings.

Agri-environmental implications of N- and P-based manure application to perennial and annual cropping systems

Continuous manure application based on crop nitrogen (N) requirements could substantially increase field nutrient losses from croplands. Although phosphorus-based (P) manure application is an alternative, crops may suffer from potential microbial P immobilization and fixation of P in soil. A three-year study (2012–2014) was carried out in Manitoba, Canada, to evaluate the agronomic and environmental benefits and tradeoffs between N- and P-based liquid and solid swine manure applications on previously established (2009) annual (ACS) and perennial (PCS) cropping systems. The N-based solid manure produced greater aboveground biomass and grain yields of barley than the unfertilized control in the ACS. The N-based liquid manure produced greater biomass than the control in the PCS. Phosphorus-based treatments produced statistically similar canola oilseed grains as the N-based treatments. Seeding the PCS to canola in 2013 produced greater aboveground biomass yields than the ACS; however, the canola oilseed yields were not significantly different between the two systems. The N-based solid manure application increased Olsen P by approximately 30 mg kg−1 in both cropping systems during the three-year study period. Both N- and P-based liquid manure treatments and the N-based solid manure treatment lost significantly greater nitrate through leaching than the control in 2013, when most leaching losses occurred. Our study also showed that some of the environmental benefits of the perennial cropping system, such as reduced nitrate leaching, could be lost when converted to an annual cropping system.

Development of Kinetic Parameters for Nitric Acid Leaching of Phlogopite and the Characterization of Solid Products

AbstractSouth Africa is a net importer of fertilizer products, importing all of its potassium, as well as 60–70% of its nitrogen requirements. Thus, domestic prices are impacted significantly by international prices, shipping costs, and exchange rates. Producing these fertilizers locally would be far more economical. Phlogopite, a rich source of potassium, is discarded in large quantities during mining operations; the objective of the present study, therefore, was to determine the acid-leaching characteristics and behavior of phlogopite as a means of releasing potassium. Phlogopite samples were leached with nitric acid (source of nitrogen for fertilizers) at various concentrations, temperatures, and reaction times. The feed phlogopite and leached residue samples corresponding to conversions of 14% (LP1), 44% (LP2), and 100% (LP3) were collected and analyzed using X-ray fluorescence spectroscopy (XRF), X-ray diffractometry (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Brunauer–Emmett–Teller surface area and porosity analysis (BET), thermogravimetric analysis (TGA), and field emission gun-scanning electron microscopy (FEG-SEM). The feed phlogopite was highly crystalline. The absence of defects in the lattice meant that the motion of H+ atoms penetrating into the lattice was restricted, suggesting internal diffusion-controlled leaching. Furthermore, results obtained from the various analytical techniques corroborated each other in terms of the release of cations during leaching. All leaching experiments were conducted batchwise, in a closed system. The gravimetric data from the experiments were used to identify a suitable model which predicts accurately the leaching behavior. The reaction was found to be internal diffusion-controlled, and the D1 model, which represents one-dimensional diffusion through a flat plate, predicts the leaching behavior most accurately. The observed activation energies (Ea) and pre-exponential constants (k0) varied with initial nitric acid concentration ([H+]0).

A novel approach for determining nitrogen requirement based on a new agronomic principle—sugarcane as a crop model

A novel approach for determining nitrogen requirement based on a new agronomic principle—sugarcane as a crop model

Effect of Yeast Assimilable Nitrogen Content on Fermentation Kinetics, Wine Chemical Composition and Sensory Character in the Production of Assyrtiko Wines

Two wild-type Saccharomyces cerevisiae yeast strains (Sa and Sb) were tested for white wine production using Assyrtiko grape of Santorini. A third commercial Saccharomyces strain was also studied for comparison reasons. Two concentrations of yeast extract and diammonium phosphate (DAP) were added to the must (150 and 250 mg/L) in order to evaluate the effect of nitrogen content on the final wine quality. Analytical methods (HPLC, GC-MS) and sensory analysis were employed to assess the quality of the wines. Fermentation kinetics were monitored throughout the experiment. By the second day of fermentation, all strains showed an approximate consumption of 70% of amino acids. Differences among strains were observed regarding inorganic nitrogen requirements. Sb strain resulted in higher concentrations of higher alcohols (1.9-fold) and ketones (5.6-fold) and lower concentrations of esters (1.2-fold) compared to the control, while Sa strain resulted in higher content of fatty acids (2.1-fold). Both indigenous strains scored better results in aroma quality, body and acidity compared to control. The overall evaluation of the data highlights the great potential of the indigenous S. cerevisiae strains as fermentation starters providing promising results in the sector of terroir wines.

Response of Posidonia oceanica (L.) Delile and Its Associated N2 Fixers to Different Combinations of Temperature and Light Levels

The increasing occurrence of heat waves and water turbidity are threats to the persistence of seagrass meadows. Their effects on the productivity of seagrasses and the functioning of their associated microorganisms have not been studied extensively. The purpose of this study is to assess the effects of different light levels and temperatures onPosidonia oceanica; the endemic seagrass species in the Mediterranean Sea, and their N2-fixing community, which contributes importantly to the nitrogen requirements and high productivity of the plants. Aquarium experiments were conducted in winter, when the plants are more vulnerable to changes in temperature, subjecting them to short-term exposures to an ambient (15.5°C) and elevated temperatures (ambient+5.5°C), and at limited (13 μmol photons m−2s−1) and saturating light conditions (124 μmol photons m−2s−1). Primary production, chlorophyll content, reactive oxygen species production, polyphenols content, thenifHgene expression, N2fixation, and alkaline phosphatase activities were measured in different plant tissues. Plants incubated at ambient temperature and high light exhibited an enhanced total chlorophyll production. Significantly higher gross and net primary production rates were also recorded under ambient temperature and high light conditions, which were approximately two-fold compared to the rest of the treatments. The oxidative stress analyses revealed an increased production of reactive oxygen species in young leaves incubated at ambient temperature and saturating light, while the polyphenols content in top leaves was considerably higher under elevated temperatures. In contrast, the N2fixation and alkaline phosphatase rates were significantly higher under elevated temperature and low light levels. The presence of the N2-fixing phylotypes UCYN-A, -B, and -C was detected through genetic analyses, with UCYN-B demonstrating the highestnifHgene transcription levels at elevated temperatures. These findings emphasize the significant role of irradiance on the productivity ofP. oceanicaand the temperature dependence of the N2fixation process in winter.

Prominent Doses of Nitrogen Enhance Mulberry and Silk Cocoon Productivity

Nitrogen (N) has potential to improve leaf yield and quality of mulberry plant. However, optimum doses of N for mulberry cultivation have not been updated for long times on the newly developed mulberry varieties in Bangladesh. A study was conducted at the research field and laboratories of Bangladesh Sericulture Research and Training Institute (BSRTI), Rajshahi to determine the nitrogen (N) requirements and optimum age of mulberry plants to get higher leaf yield, better quality of leaves, successful silkworm rearing performance and suppresses of foliar diseases in mulberry plant. The six treatments executed for trials on N requirements of mulberry plants were: N: 0, 80, 160, 240, 320 and 400 kg/ha/yr. The blanket doses of P & K for N trial were fixed as per recommended doses of BSRTI. Research results indicated that the added nutrient elements (N) favored in increasing growth, leaf yield, improving quality of mulberry leaves, suppresses foliar diseases as well as improved silk cocoon productivity. The leaf yield increased with increased rates of N application. The highest leaf yield was 51.88 Mt/ha/yr found in older plants of 6-10 years of age with the application of N @ 400 kg/ha/yr which was 6.57% higher than the maximum average yield of less than 5 years ages of mulberry plant. All the growth and quality parameters of leaves viz: moisture, chlorophyll-a, chlorophyll-b, total sugar, soluble carbohydrate, reducing sugar and crude protein exhibited the best performance with the better silkworm rearing performances viz: wt. of 10 matured larval (g), effective rate of rearing by number, single cocoon wt. (g), single shell wt. (g), SR%, highest filament length (m), rendita and cocoon yield/100 dfls (kg) through the treatment of N400 P150 K100 kg/ha/yr (T5) with four split doses in 6-10 years ages of mulberry plant, where the cocoon productivity was 57.85% greater than the control treatment. Furthermore, the average incidence percentages of leaf spot, tukra and powdery mildew diseases were also reduced for the increasing doses of nitrogen. This study concluded that elevated N enhances mulberry leaf yield, quality, silk cocoon productivity as well as suppresses the foliar diseases incidence of mulberry plant.

Interactive effects of level of nitrogen and irrigation application on maize yield

Maize (Zea mays L.) yields are recognized to be sensitive to both the level of nitrogen fertilization and irrigation that is applied to the crop. However, there are virtually no studies where experimental results are analyzed to quantitatively explore directly the interactive influence of these two resources on yield. As a consequence, it is difficult to sort out the optimum management regime for the available resources. A polynomial regression analysis was applied to results from seven field experiments involving several nitrogen and irrigation treatments. The polynomial equation included for each resource a linear term and second-order term plus a multiplicative term of the two resources. The polynomial regression fit very well the results of all experiments (R2 ≥ 0.86). The impact of irrigation included the linear term in all experiments (p ≤ 0.017). In all but one experiment, yield was also linearly dependent on amount of nitrogen application. The polynomial expression led to determination of the nitrogen fertilization required for maximum yield as being dependent on level of irrigation. In all cases, increased irrigation amounts resulted in an increased nitrogen requirement to achieve maximum yield. Another important outcome of the analysis was that the multiplicative term for irrigation x nitrogen was generally important in describing yield. These results demonstrate the inadequacy of attempting to define the results of such multiple-factor experiments based on a single limiting-factor approach.

Saturating relationship between phytoplankton growth rate and nutrient concentration explained by macromolecular allocation.

Phytoplankton account for about a half of photosynthesis in the world, making them a key player in the ecological and biogeochemical systems. One of the key traits of phytoplankton is their growth rate because it indicates their productivity and affects their competitive capability. The saturating relationship between phytoplankton growth rate and environmental nutrient concentration has been widely observed yet the mechanisms behind the relationship remain elusive. Here we use a mechanistic model and metadata of phytoplankton to show that the saturating relationship between growth rate and nitrate concentration can be interpreted by intracellular macromolecular allocation. At low nitrate levels, the diffusive nitrate transport linearly increases with the nitrate concentration, while the internal nitrogen requirement increases with the growth rate, leading to a non-linear increase in the growth rate with nitrate. This increased nitrogen requirement is due to the increased allocation to biosynthetic and photosynthetic molecules. The allocation to these molecules reaches a maximum at high nitrate concentration and the growth rate ceases to increase despite high nitrate availability due to carbon limitation. The produced growth rate and nitrate relationships are consistent with the data of phytoplankton across taxa. Our study provides a macromolecular interpretation of the widely observed growth-nutrient relationship and highlights that the key control of the phytoplankton growth exists within the cell.

Nutritional requirements and precise fertilization of wine grapes in the eastern foothills of Helan Mountain

Cabernet Sauvignon grapes in the wine-producing area of Helan Mountain, East Ningxia, China, were the research object in this study. The dissection of the roots and branching stems method was used to explore the dynamic changes in the nitrogen, phosphorus, and potassium nutrient requirements of wine grapes over a number of growth stages. The results showed that over the whole growth period, the nitrogen content of the roots was the highest during the leaf-expansion stage and lowest during the turning-color stage, and that the nitrogen content of the leaves and fruit showed a downward trend as growth progressed. The nitrogen content of the secondary branches was lowest during the fruit expansion stage and highest during the leaf-expansion stage; and the phosphorus content of the roots was the highest during the leaf-expansion stage and lowest during the fruit expansion stage. The phosphorus content of the trunk and primary branches showed a trend of “rising-falling-rising”. The phosphorus content of the leaves and secondary branches were lowest during the turning-color stage, whereas the phosphorus content of the fruit was at its highest during this stage. The potassium contents of the secondary branches and fruit showed a downward trend, but the potassium content of the leaves was highest during the fruit expansion stage and lowest in the nutrient return stage. Over the whole growth period, the accumulation of nitrogen, phosphorus, and potassium in wine grapes was 129.92 kg/hm2, 41.51 kg/hm2, and 189.47 kg/hm2, respectively, the total requirements for N, P2O5, and K2O were 262.38 kg/hm2, 288.15 kg/hm2, and 569.04 kg/hm2, respectively, and the reasonable nutrient requirement ratio was 1.00:1.10:2.17. Keywords: wine grapes, macronutrients, nutritional diagnosis, fertilizer requirements, the eastern foot of Helan Mountain DOI: 10.25165/j.ijabe.20221504.5406 Citation: Jiang T T, Yan P K, Ma T H, Wang R. Nutritional requirements and precise fertilization of wine grapes in the eastern foothills of Helan Mountain. Int J Agric & Biol Eng, 2022; 15(4): 147–153.

Effects of Nitrogen Exponential Fertilization on Growth and Nutrient Concentration of Hydrangea macrophylla Seedlings

Slow growth rate restricts the development and growth of seedlings due to nutrients deficiency or nutrient imbalance. Exponential fertilization can enhance the internal nutrient reserves in seedlings at the nursery-stage and strengthen their resistance to adverse conditions. In this study, nitrogen requirements for producing Hydrangea macrophylla ‘Hanatemari’ that robust seedlings, nutrient dynamics, biomass and growth, was examined utilizing exponential fertilization. The potted seedlings were fertilized with urea under exponential regime at rates of 0.5, 1.5 and 2.0 g nitrogen/plant (EF1, EF2, and EF3), respectively. In addition, an unfertilized group treated with equal volume of deionized water was used as control. The results showed that seedlings under 1.5 g N/plant (EF2) had the highest plant growth index and total biomass. The nutrient concentrations of different organs varied in different fertilization treatments. Based on the results of current study, it is concluded that 1.5 g N/plant (EF2) is suitable exponential fertilization treatment for the culture of hydrangea seedlings. Our treatments results showed that 2.0 g N/plant is not suitable for seedling culturing, because of serious nutrient toxicity. These findings will help to improve seedling quality and strengthen the production of H. macrophylla for plantation.

Determining nitrogen deficiencies for maize using various remote sensing indices

Determining a precise nitrogen fertilizer requirement for maize in a particular field and year has proven to be a challenge due to the complexity of the nitrogen inputs, transformations and outputs in the nitrogen cycle. Remote sensing of maize nitrogen deficiency may be one way to move nitrogen fertilizer applications closer to the specific nitrogen requirement. Six vegetation indices [normalized difference vegetation index (NDVI), green normalized difference vegetation index (GNDVI), red-edge normalized difference vegetation index (RENDVI), triangle greenness index (TGI), normalized area vegetation index (NAVI) and chlorophyll index-green (CIgreen)] were evaluated for their ability to detect nitrogen deficiency and predict grain maize grain yield. Strip trials were established at two locations in Arkansas, USA, with nitrogen rate as the primary treatment. Remote sensing data was collected weekly with an unmanned aerial system (UAS) equipped with a multispectral and thermal sensor. Relationships among index value, nitrogen fertilizer rate and maize growth stage were evaluated. Green NDVI, RENDVI and CIgreen had the strongest relationship with nitrogen fertilizer treatment. Chlorophyll Index-green and GNDVI were the best predictors of maize grain yield early in the growing season when the application of additional nitrogen was still agronomically feasible. However, the logistics of late season nitrogen application must be considered.

Legume Winter Cover Crop (Persian Clover) Reduces Nitrogen Requirement and Increases Grain Yield in Specialized Irrigated Hybrid Rice System

Legume Winter Cover Crop (Persian Clover) Reduces Nitrogen Requirement and Increases Grain Yield in Specialized Irrigated Hybrid Rice System

Modeling the Effect of Planting Dates and Nitrogen Application Rates on Potatoes Water Productivity in Jordan Valley

Agricultural sector in Jordan is facing serious challenges in meeting the growing needs of food security because of its low water availability. Maintaining and enhancing agricultural water productivity under such prevailing environmental constraints are hard to achieve. Potatoes water productively in Jordan Valley was modeled using Decision Support System for Agrotechnology Transfer (DSSAT) under six nitrogen applications (0, 60, 80, 100, 120 and 140 kg/ha) and twelve planting dates every two weeks from October 1 to March 15 scenarios. The potatoes yield increased from 0% to 100% nitrogen treatment and then no considerable increase occurred. The potatoes’ crop yield increased from October 1st to January 15 and then decreased after which until the last day of planting date. The seasonal cumulative crop evapotranspiration for potatoes about doubled from 0% to 60% nitrogen treatment and then kept increasing gradually until the last treatment. The growing season cumulative crop evapotranspiration for potatoes increased gradually from October 1 to March 1. The water productivity increased from 0% nitrogen treatment to 100% and then decreased. The potatoes’ water productivity increased from October 1 until November 15 and then decreased to the end. From these results, we recommend that 100% of nitrogen requirements should be applied. The best window for potatoes’ planting date is the last two weeks in November.

Combining targeted grass traits with red clover improves grassland performance and reduces need for nitrogen fertilisation

To increase ruminant production efficiency, the environmental impact of growing forage must be reduced, through lowering system inputs and increasing crop resilience to extreme weather. Here we examined the role of red clover (cv. AberClaret) in minimising nitrogen (N) requirements, alongside two novel grass varieties, (1) a festulolium (cv. AberNiche), developed for drought tolerance, with potential for deep-rooting, and (2) a ryegrass hybrid (cv. AberEcho), developed for high-sugar content, which may enhance ruminant N-uptake in-vivo. Field trials were conducted at two UK sites, growing festulolium and ryegrass ± red clover (at 29% of the seed mix weight) at a range of N fertilisation rates (0 – 600 kg N ha−1) for 2 years (six harvests). We assessed sward performance (N offtake, herbage quality, and grass N use efficiency), rooting depth and N transfer from clover to grasses using 15N natural abundance. Across both sites and years, dry matter yield and herbage-N content were overall greater from the swards that included clover. Dry matter yields from festulolium were not greater than from ryegrass under the drought conditions experienced in 2018, despite its greater root mass. Agronomic efficiency of fertiliser N was similar between grasses (19 – 22%), however the festulolium more effectively used endogenous soil N than the ryegrass. Inclusion of clover in the sward affected forage quality, with increased crude protein and metabolisable energy content and reduced sugar and fibre (NDF) content. Among the grass types, metabolisable energy was greater and NDF content less for ryegrass than for festulolium. A strong reliance on biological N fixation (80 – 94%) for clover was observed, however, N transfer from clover to the neighbouring grass was not evident from the ẟ15N signatures. We conclude that red clover is a viable fertiliser-N replacement strategy in short-term leys, and that grass varieties with improved herbage quality may provide a better option for optimising sward performance than drought tolerant grass varieties.