Crop Uptake Research Articles

Nitrogen dynamics in soils fertilized with digestate and mineral fertilizers: A full field approach

Highly stabilized digestate from sewage sludge and digestate-derived ammonium sulphate (RFs), were used in a comparison with synthetic mineral fertilizers (SF) to crop maize in a three-year plot trial in open fields. RFs and SF were dosed to ensure the same amount of mineral N (ammonia-N). In doing so, plots fertilized with digestate received much more N (+185 kg ha−1 of organic N) because digestate also contained organic N. The fate of nitrogen was studied by measuring mineral and organic N in soil at different depths, ammonia and N2O emissions, and N uptake in crops. Soil analyses indicated that at one-meter depth there was no significant difference in nitrate content between RF, SF and Unfertilized plots during crop season indicating that more N dosed with digestate did not lead to extra nitrate leaching. Ammonia emissions and N content in plants and grains measured were also similar for both RF and SF. Measuring denitrification activity by using gene makers resulted in a higher denitrification activity for RF than SF. Nevertheless, N2O measurements showed that SF emitted more N2O than RF (although it was not statistically different) (7.59 ± 3.2 kgN ha−1 for RF and 10.3 ± 6.8 kgN ha−1 for SF), suggesting that probably the addition of organic matter with digestate to RF, increased the denitrification efficiency so that N2 production was favoured. Soil analyses, although were not able detecting N differences between SF and Rf after three years of cropping, revealed a statistical increasing of total carbon, suggesting that dosing digestate lead to carbon (and maybe N) accumulation in soil. Data seem to suggest that N2O/N2 emission and organic N accumulation in soil can explain the fate of the extra N dosed (organic-N) in RF plots.

Isotopic evaluation of in‐season Y Drop applications for corn production

AbstractA common strategy for improving fertilizer N uptake efficiency by corn (Zea mays L.) is to synchronize application with crop N demand during the growing season, which can be done using the Y Drop system recently developed for surface dribble placement. A 2‐yr field study was conducted using dual‐labeled urea‐ammonium nitrate (UAN) solution to compare fertilizer 15N uptake efficiency (F15NUE) for surface and subsurface sidedress applications to soils of contrasting fertility under either second‐year corn or a corn–soybean [Glycine max (L.) Merr.] rotation. Besides placement, treatments were designed to allow comparison of 15N uptake from UAN applications made at planting vs. at the V9 growth stage. The importance of soil N supply was demonstrated by estimates of N derived from fertilizer that ranged from 17 to 47% in total aboveground biomass and never exceeded N derived from soil. Of the fertilizer N recovered in the crop at harvest, the majority originated from the 15N applied at sidedressing rather than at planting. The range in F15NUE was from 12 to 42% (26% on average) for grain and from 14 to 51% (31% on average) for total aboveground biomass, the only significant difference occurring when the subsurface treatment outperformed Y Drop placement under conditions conducive to urea N loss through NH3 volatilization. Both methods of application offer the same fundamental advantage, in that fertilizer N is supplied during the period of maximal crop uptake.

Biochar reduces uptake and accumulation of polycyclic aromatic hydrocarbons (PAHs) in winter wheat on a PAH-contaminated soil

Biochar has been used previously for remediation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soils for years, which has achieved remarkable results in improving removal of soil PAHs and reducing PAHs uptake in crops. However, the underlying mechanism of biochar application in reducing the uptake and accumulation of PAHs in winter wheat remains unclear. Pot trials using PAHs-contaminated soils were conducted for whole plant growth period of winter wheat, which were amended with 2% (w/w) bamboo biochar (BB), coconut shell biochar (CB) and maize straw biochar (MSB) or not (CK). Compared with CK, application of the three types of biochar significantly (p < 0.01) reduced grain PAHs concentration, the total equivalent concentration (TEC) values and the incremental lifetime cancer risk (ILCR) of grain PAHs, indicating that application of biochar reduced the exposure risk of PAHs in wheat grain, especially for MSB. Consistently, application of the three types of biochar significantly (p < 0.05) reduced uptake and accumulation of PAHs in root and stem of wheat, which may be due to that application of biochar enhanced the degradation of PAHs in the rhizosphere soil. Compared with CK, application of the three types of biochar significantly (p < 0.05) reduced the concentration of PAHs in the rhizosphere soil by 15.9%, 26.1% and 33.7%, respectively. It was found that the degradation rate of HMW PAHs (high molecular weight PAHs, 5-6 ring PAHs) was significantly (p < 0.05) higher than that of LMW PAHs (low molecular weight PAHs, 2-4 ring PAHs) regardless of types of biochar used. Additionally, application of the three types of biochar significantly increased the relative abundance of dominant bacterial phyla and genera in soil. Redundancy analysis and correlation analysis results also showed that there was a strong correlation between the removal rate of PAHs and dominant bacteria in the rhizosphere soil. The present study indicated that biochar could reduce dietary risk of PAHs in wheat grains mainly by increasing the abundance of bacteria related to PAHs degradation, promoting the biodegradation of PAHs in the rhizosphere soil and consequently reducing PAHs uptake in wheat.

Impact of Microbial Inoculants and Fertilizers on Nutrient Uptake and Yield of Sugarcane Short Crop

A field experiment was conducted at Agricultural Research Station, Perumallapalle, Tirupati, Acharya N. G. Ranga Agricultural University, Andhra Pradesh, India during 2021-22 to study the effect of microbial inoculants and fertilizers on nutrient uptake and yield of sugarcane short crop. The experiment was laid out in randomized block design with ten treatments and replicated thrice. The treatments consist of 75%, 100% and 125% RDF in combination of solid and liquid microbial inoculants (Gluconacetobacter, PSB and KSB). Data on N, P, K and S uptake by plant at different stages and yield were recorded. Results revealed that application of 100% RDF along with sett treatment with liquid Gluconacetobacter @ 1 lit ha-1, PSB @ 1 lit ha-1 and KSB @ 1 lit ha-1 resulted significantly the highest N, P, K and S uptake by plant and seed cane yield followed by 100% RDF + sett treatment with solid Gluconacetobacter @ 10 kg ha-1, PSB @ 1.25 kg ha-1 and KSB @ 1.25 kg ha-1.

Migration of Soil Ammonium- Nitrogen with Amended Poultry and Sheep Manures in Ultisols of Ihiagwa, Southeastern Nigeria

Soil management to synchronizing nutrient release with crop uptake is essential for sustainable plant production and environmental quality. Ammonium- nitrogen (NH4+- N) dynamics of poultry and sheep manures amended Ultisols in Ihiagwa, Southeastern Nigeria were evaluated. Their levels equivalent to 0, 30 and 60 % N of both poultry and sheep manures were applied in a 32 factorial arranged in randomized complete block setup with three replications. The NH4+- N was determined from four soil depths (0 – 5, 5 – 10, 10 – 20 and 20 – 40 cm) at different weeks (1, 2, 3, 4, 6, 8 and 12 weeks) after manures application (WAMA) in wet and dry seasons of 2019 and 2020. Soil NH4+- N differed with rates of poultry and sheep manures only and the integration of both manure at various soil depths, seasons and years. Concentrations of NH4+- N in most soil depths at both seasons and years were better with 60 % then 30 % N of poultry and sheep manures alone and with integrations of both manures better than single applications. Averaged over soil depths and periods after manure applications, soil ammonium- nitrogen was better in wet than dry seasons and in 2019 than 2020. Averaged over soil depths, manure rates, seasons and years, concentrations of NH4+- N varied and better at 3rd WAMA. Equally, concentrations of NH4+- N decreased down soil depths. Generally, good soil nutrient management will be useful for efficiency of nutrient and sustained crop yields. Further research is needed on the field to substantiate the findings.

Assessment of Nutrient Leaching Losses and Crop Uptake with Organic Fertilization, Water Saving Practices and Reduced Inorganic Fertilizer

The increasing world population has forced excessive chemical fertilizer and irrigation to complete the global food demand, deteriorating the water quality and nutrient losses. Short-term studies do not compile the evidences; therefore, the study aimed to identify the effectiveness of reduced doses of inorganic fertilizer and water-saving practices, hence, a six-year experiment (2015–2020) was conducted in China to address the knowledge gap. The experimental treatments were: farmer accustomed fertilization used as control (525:180:30 kg NPK ha−1), fertilizer decrement (450:150:15 kg NPK ha−1), fertilizer decrement + water-saving irrigation (450:150:15 kg NPK ha−1), application of organic and inorganic fertilizer + water-saving irrigation (375:120:0 kg NPK ha−1 + 4.5 tones organic fertilizer ha−1), and application of controlled-release fertilizer (80:120:15 kg NPK ha−1). Each treatment was replicated thrice following a randomized complete block design. The results achieved herein showed that control has the highest losses in the six-year study for total nitrogen (225.97 mg L−1), total soluble nitrogen (121.58 mg L−1), nitrate nitrogen (0.93 mg L−1), total phosphorus (0.57 mg L−1), and total soluble phosphorus (0.57 mg L−1) respectively. Reduced fertilizer and water application improved crop nutrient uptake, nitrogen concentration was significantly enhanced with organic and inorganic fertilizer + water-saving irrigation, P concentration was increased with fertilizer decrement + water-saving irrigation, and K concentration was improved with fertilizer decrement + water-saving irrigation. Hence, this study concludes that reduced inorganic fertilizer dose combined with water-saving practices is significantly helpful in reducing nutrient leaching losses and improving nutrient uptake and water pollution. Further studies are needed to explore the impacts of reduced fertilization and water-saving irrigation on leaching losses. The benefits at different climatic conditions, soil types, and fertilizer types with application methods are also a research gap.

Mycorrhizal fungi and soil factors influence toxic element uptake in urban grown produce

AbstractDespite the need for more urban‐grown produce, toxic elements contaminated soils continue to be a major barrier to food production and food sovereignty in urban areas and a continued health and environmental justice issue. Although the US EPA provides recommendations regarding levels of soil lead that are safe for gardening, soil abiotic and biotic factors as well as plant identity play a major role in determining the actual crop uptake of toxic elements. This study evaluated the role of crop identity, harvested tissue, and soil factors, including arbuscular mycorrhizal (AM) fungi on crop uptake of lead (Pb) and arsenic (As) in an urban community farm. Crop species varied in their Pb and As accumulations, both by crop identity and also by plant tissue. Crop uptake of lead increased with lower soil pH (range 5.3–6.9) and lower soil P (range 365–1771 mg kg−1 total P). For mycorrhizal crops, greater intensity of AM fungal colonization and the prevalence of arbuscules were associated with greater lead uptake, but the presence of more storage vesicles was related to less As uptake into leaves. These findings can help inform crop selection and soil management to improve soil stabilization of toxic elements in moderately contaminated soils while serving as a platform for community conversations about the importance of soil management in healthy urban food production.

Beneficial Effects of Biochar Application with Nitrogen Fertilizer on Soil Nitrogen Retention, Absorption and Utilization in Maize Production

The irrational use of nitrogen (N) fertilizer has become a major threat to soil quality and food security, resulting in serious ecological and environmental problems. Holistic approaches to N fertilizer application are required to maintain a high N utilization efficiency (NUE) and sustainable agriculture development. Biochar is an efficient carbon-rich material for amending soil quality and promoting crop N uptake, but knowledge pertaining to the promoting effects of biochar application on N fertilizers is still limited. In this study, a field plot experiment was designed to detect the combined effects of biochar (0, 15 and 30 t ha−1) and N fertilizer (204, 240 and 276 kg N ha−1) on the soil nutrient levels, NUE, plant growth performance and crop production of maize. The results demonstrated that the combined application of N fertilizer and biochar can significantly decrease the soil pH and increase the contents of soil organic carbon, mineral N, available phosphorus and potassium. The crop N uptake and N content were largely promoted by the addition of N fertilizer and biochar, resulting in higher leaf photosynthetic efficiency, dry matter accumulation and grain yields. The highest yields (14,928 kg ha−1) were achieved using 276 kg N ha−1 N fertilizer in combination with 15 t ha−1 biochar, and the highest NUE value (46.3%) was reached with 204 kg N ha−1 N of fertilizer blended with 30 t ha−1 of biochar. According to structural equation modeling, the beneficial effects of N fertilizer and biochar on the plant biomass of maize were attributed to the direct effects related to soil chemical properties and plant growth parameters. In conclusion, N fertilizer combined with biochar application is an effective strategy to enhance the utilization of N fertilizer and crop production for maize by increasing soil fertility, improving plant crop uptake and promoting plant growth.

An LSTM‐based mixed‐integer model predictive control for irrigation scheduling

AbstractThe development of well‐devised irrigation scheduling methods is desirable from the perspectives of plant quality and water conservation. Accordingly, in this article, a mixed‐integer model predictive control system is proposed to address the daily irrigation scheduling problem. In this framework, a long short‐term memory (LSTM) model of the soil–crop–atmosphere system is employed to evaluate the objective of ensuring optimal water uptake in crops while minimizing total water consumption and irrigation costs. To enhance the computational efficiency of the proposed method, a heuristic method involving the logistic sigmoid function is used to approximate the binary variable that arises in the mixed‐integer formulation. Through computer simulations, the proposed scheduler is applied to homogeneous and spatially variable fields. The results of these simulation experiments reveal that the proposed method can prescribe optimal/near‐optimal irrigation schedules that are typical of irrigation practice within practical computational budgets.

Remediation of uranium-contaminated alkaline soil by rational application of phosphorus fertilizers: Effect and mechanism

In alkaline soil, abundant carbonates will mobilize uranium (U) and increase its ecotoxicity, which is a serious threat to crop growth. However, the knowledge of U remediation in alkaline soils remains very limited. In this study, U-contaminated alkaline soil (tillage layer) was collected from the Ili mining area of Xinjiang, the soil remediation was carried out by using phosphorus (P) fertilizers of different solubility (including KH2PO4, Ca(H2PO4)2, CaHPO4, and Ca3(PO4)2), and the pathways and mechanisms of U passivation in the alkaline soil were revealed. The results showed that water-soluble P fertilizers, KH2PO4 and Ca(H2PO4)2, were highly effective at immobilizing U, and significantly reduced the bioavailability of soil U. The exchangeable U was reduced by 70.5 ± 0.1% (KH2PO4) and 68.2 ± 1.9% (Ca(H2PO4)2), which was converted into the Fe–Mn oxide-bound and residual phases. Pot experiments showed that soil remediation by KH2PO4 significantly promoted crop growth, especially for roots, and reduced U uptake in crops by 94.5 ± 1.0%. The immobilization of U by KH2PO4 could be attributed to the release of phosphate anions, which react with the uranyl ion (UO22+) forming a stable mineral of meta-ankoleite and enhancing the binding of UO22+ to the soil Fe–Mn oxides. In addition, KH2PO4 dissolution produces acidity and P fertilizer, which can reduce soil alkalinity and improve crop growth. The findings in this work demonstrate that a rational application of P fertilizer can effectively, conveniently, and cheaply remediate U contamination and improve crop yield and safety on alkaline farmland.

Continuous application of biochar increases 15N fertilizer translocation into soil organic nitrogen and crop uptake in drip-irrigated cotton field

Continuous application of biochar increases 15N fertilizer translocation into soil organic nitrogen and crop uptake in drip-irrigated cotton field

Growth and Yield of Okra Exposed to a Consortium of Rhizobacteria with Different Organic Carriers under Controlled and Natural Field Conditions

Crop yields, soil fertility, and soil quality decline due to the overuse of chemical fertilizers and other agrochemicals. The damaging effects of these agrochemicals on the environment can be minimized by integration with eco-friendly approaches, i.e., biofertilizers. These eco-friendly biofertilizers containing plant growth-promoting rhizobacteria, (PGPR) not only solubilize mineral nutrients for crop uptake but also release phytohormones for their growth improvements. The objective of this research is to use these PGPR’s capacity to promote growth in order to increase okra production. For this purpose, different organic carriers were used, i.e., Press mud, Charcoal, Biochar, Peat, and Compost for PGPR’s inoculation. Before being used as a consortium with various carrier materials, the pre-isolated and characterized PGPR strains (AN-35, ZM-27, and ZM-63) were tested for compatibility against one another. The PGPR consortium and carriers were applied in the following treatments, i.e., T0: (control), T1: PGPR, T2: Peat + PGPR, T3: Pressmud+ PGPR, T4: Compost + PGPR, T5: Charcoal + PGPR, and T6: Biochar + PGPR in the present pot and field studies. Under the pot experiment, the results depicted that all treatments showed a significant increase in okra growth, nutrient contents, and yield of okra along with increasing the microbial biomass in the soil but the treatment containing PGPR consortium with peat caused the maximum increase. Similarly, the results of the field experiment also showed a significant increase under all treatments but the maximum increase in nutrient contents, growth attributes, and yield of okra was found under the treatment containing PGPR consortium with peat (T2). Therefore, this study recommends the use of peat and studied the PGPR consortium as a suitable carrier to develop carrier-based biofertilizers for sustainable okra production.

Response of Seed Size and Bio-fertilizer on Yield, Quality, Nutrient Content and Uptake of Groundnut Crop under Rainfed Condition

A field experiment was conducted during kharif season 2021 to study the effect of seed size and bio-fertilizers on yield, quality, nutrient content and uptake by the crop and available nutrients in soil after harvest of crop. The treatments include different categories of seed size viz., mixed (S1), bold (S2) and small seed size (S3) and bio-fertilizer viz., control (B1), Rhizobium + PSB + KMB (B2) and Trichoderma harzianum + Aspergillus niger (B3). Seed yield and haulm yield of groundnut were significantly increased by the treatments of seed size and biofertilizers. The crops sown with large seed size (1184 kg ha-1) and bio-fertilizer with the treatment Rhizobium + PSB + KMB produced significantly higher seed yield (1227 kg ha-1). Similarly, significantly higher haulm yield was also found in the treatment large seed (2442 kg ha-1) and Rhizobium + PSB + KMB (2427 kg ha-1). However, oil content and oil yield were found non-significant by seed size and bio-fertilizer. Significantly higher nutrient uptake by seed and haulm of crop obtained with the treatment bold seed and Rhizobium + PSB + KMB.

Residual effect of biofortified iodine in soil, plant, crop yield and quality of tomato (Solanum lycopersicum L.)

When iodine levels in the soil are inadequate, resulting in limited crop uptake and as a result, a population with insufficient iodine intake. Iodine deficiency can be avoided by biofortifying commonly consumed crops with iodine. Tomato is the best crop for biofortification study as it is having the capacity to store excess iodine in pholoem. The field experiment was carried out in Thondamuthur block of Viraliyur village at Coimbatore district of Tamil Nadu in 2021. The purpose of this study was to determine the effect of biofortication of iodine in residual tomato growth, yield, quality and iodine content. Potassium iodate and Chitosan were applied in the form of soil, foliar and Chitosan iodate complex at different stages of plant growth. The results revealed that the soil fertilization of potassium iodate alone resulted in lower uptake of residual iodine in fruits because the iodine was susceptible to high volatilization and less phyto-availability. While foliar spray alone increased the residual iodine content in roots and stem. However, residual higher iodine accumulation in the tomato fruits was achieved through the combination of foliar and iodine Chitosan forms. As electrostatic interaction between Chitosan and iodate prevents volatilization and gradually increases the bioavailability of iodine from soil to fruits. Based on the discussion, biofortification of iodine through potassium iodate Chitosan complex paved the way for the improvement of growth, yield, quality and iodine content in fruits. Hence, biofortification of iodine through iodate Chitosan complex increased the iodine content in tomato fruit and introducing it in our daily diet may be helpful to reduce iodine deficiency disorder.

Response of groundnut to phosphorus and bio-organics in Alfisols of Red and Laterite zone of India

Present study was carried out for three consecutive kharif season of 2018, 2019 and 2020 to evaluate the performance of different levels of chemical phosphatic fertilizers and FYM in combination with PSB inoculant on groundnut growth, yield, quality and nutrient uptake in an acidic Red and Laterite soil. Application of higher dose of phosphatic fertilizer along with PSB inoculant yielded better results with respect to groundnut plant height, nodulation, pegs and pods plant−1, weight of mature pods plant−1, kernel and haulm yield, protein and oil content, and nutrient uptake. Treatment combination T7 (60 kg ha−1 of P2O5 + PSB inoculant) was observed as the best treatment combination for deriving maximum growth, yield and nutrients uptake of kharif groundnut crop. Treatment T6 (application of 40 kg ha−1 of P2O5 + PSB inoculant) reported similar results. However, maximum profit ($862), benefit cost ratio (2.7) and net return per unit cost of input was significantly higher in T7 compared to T6. Thus, we recommend application of 60 kg ha−1 of P2O5 with PSB inoculant (T7) for the light textured acid soils of Red and Laterite zone of India for higher production and profitability.

Impact of zinc on yield, nutrient uptake and soil nutrient status in rainfed pea-maize sequence under high phosphorus regime soils of Northwestern Himalaya

Field trials were conducted at the experimental farm of Hill Agricultural Research and Extension Center, Bajaura, Kullu, during kharif (summer crop) and rabi (winter crop) seasons from 2014–2015 to 2015–2016 to investigate the impact of zinc (Zn) on yield, nutrient uptake and soil nutrient status in rainfed pea-maize sequence under high phosphorus regime soils of Northwestern Himalaya. The various priming levels of Zn (water soaking- without zinc, 1%, 2% and 3% of ZnSO4) with three priming durations (4, 8 and 12 hours) were compared with basal dose of recommended NPK + ZnSO4 @ 25 kg ha−1 and farmers’ practice (absolute control). The yield of pea crop was maximum with 1% ZnSO4 priming duration of 12 hours, whereas maize crop yield was highest with 2% ZnSO4 priming duration of 12 hours. The nitrogen (N), phosphorus (P) and potassium (K) uptake of pea pods and stover was highest with 1% ZnSO4 priming for 12 hours duration, whereas the N, P and K uptake of maize grains and stover was registered highest with 2% ZnSO4 priming for a period of 12 hours. The results showed a positive impact on the crop yield and uptake, while no significant improvement was noticed in soil nutrients status after harvest.

Effect of Enterobacter sp. EG16 on Selenium biofortification and speciation in pak choi (Brassica rapa ssp. chinensis)

Using plant growth promoting rhizobacteria (PGPR) to boost Se uptake and accumulation in crops is a promising recent approach to biofortification. Most studies, however, have focused on a certain dose of PGPR or Se, while the synergistic effects of simultaneously changing the concentration of both exogenous Se and PGPR on plant growth and Se bioaccumulation are rarely explored. In this study, the combined treatments of 0-2 mg L−1 Se and (3.83-11.3) ×107 CFU mL−1 PGPR strain Enterobacter sp. EG16 were used for the hydroponic experiments of pak choi (Brassica rapa) to investigate the mutual effects on plant growth and Se absorption. The growth of pak choi, in terms of plant height, number of leaves and root tips, was promoted by combining 7.65×107 CFU mL−1 EG16 and no more than 1 mg L−1 of Se. Growth was significantly inhibited when the concentration of EG16 was raised to 11.3×107 CFU mL−1. Chlorophyll content, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities were also boosted under the same combination of Se and EG16 concentrations. In addition, the Se content of aboveground part and intact plants significantly increased with rising concentrations of EG16 and Se. Selenomethionine (SeMet), methylselenocysteine (SeMeCys) and selenocystine (SeCys2) were the main organo-Se compounds detected in pak choi, accounting for almost 90% when supplied with selenite. Among these compounds, SeMet accounted for a high proportion and SeCys2 for a relatively low percentage in most treatments. The two forms were inversely related, probably because the transformation was driven by EG16. On the other hand, the proportion of SeMeCys was significantly affected by different concentrations of exogenous Se and EG16. Selenate was also detected, indicative of selenite oxidation. In terms of both plant biomass and nutritional quality, the combined formulation of 1 mg L−1 Se and 7.65×107 CFU mL−1 of EG16 is a promising means of producing Se-enriched vegetables.

Integration of Transcriptome and Metabolome Analyses Reveals the Mechanistic Basis for Cadmium Accumulation in Maize.

Cadmium (Cd) pollution in soil has become a major environmental issue worldwide. However, the underlying molecular mechanism of low grain-Cd accumulation (GCA) in maize is still largely unknown. Herein, we report the mechanistic basis for low GCA in maize by a multiomics approach. The low GCA genotype L63 showed normal vacuolar formation and a lower capacity of xylem loading of Cd than the high-accumulator L42 under Cd stress. Transcriptomic sequencing identified 84 low-GCA-associated genes which are mainly involved in the S-adenosylmethionine (SAM) cycle, metal transport, and vacuolar sequestration. A metabolome analysis revealed that L63 plants had a more active SAM cycle and a greater capacity for terpenoid synthesis and phenylalanine metabolism than L42. Combining the analysis of transcriptome and metabolome characterized several genes as key genes involved in the determination of Cd accumulation. Our study identifies a mechanistic basis for low Cd accumulation in maize grains and provides candidate genes for genetic improvement of crops.

Nitrogen Fertilization Effects on Soil Nitrate, Water Use, Growth Attributes and Yield of Winter Wheat under Shallow Groundwater Table Condition

Shallow groundwater plays a vital role in water use and the yield of winter wheat. Nitrogen (N) application significantly affects crop uptake and utilization of water from irrigation, but little is known about groundwater use. More importantly, excessive N application will also bring a series of environmental problems. An experiment was carried out in micro-lysimeters at 0, 150, 240, and 300 kg/ha N fertilization rates based on 0.6 m groundwater depth with relatively strong alkaline soil in the winter wheat growing season. The results showed that increasing the N application rate significantly increased the sensitivity of the daily groundwater evaporation velocity of winter wheat to environmental meteorological factors (soil surface moisture, humidity, atmospheric pressure and atmospheric temperature), and promoted crop water use, crop growth and yield under the 0.6 m groundwater depth. From 150 kg/ha to 300 kg/ha N fertilization, LAI and yield increased by 26.95–82.02%, and evapotranspiration (ET) and groundwater use efficiency (GUE) increased by 11.17–14.38%. However, a high N application rate would sharply induce surface soil drought, leading to a rapid increase in nitrate accumulation in the vadose zone and a significant decrease in partial factor productivity of applied N (PFPN). With the N application of 150–300 kg/ha, the accumulation of nitrate in the vadose zone increased by 8.12 times, and soil moisture in 0–20 cm and PFPN significantly decreased by 19.16–57.53%. N fertilization had a significant effect on water transfer and could promote the consumption and utilization of groundwater at 0.6 m depth. Considering yield, water use, the accumulation of nitrate, and PFPN, the optimal N application was 219.42–289.53 kg/ha at 0.6 m depth.

Modelling the impact of the Nordic Bioeconomy Pathways and climate change on water quantity and quality in a Danish River Basin

A societal transformation towards bio-economy will have extensive implications for land use in Nordic countries. These expected changes in land use combined with a changing climate, will have unknown consequences for water quality and quantity. To address this issue, we used the Nordic Bio-economic Pathways (NBPs), which describe five possible future scenarios (NBP1-5) for the Nordic bio-economy in 2050. The NBPs were quantified by experts using local knowledge and translated into modelling scenarios. The SWAT model was applied to simulate the effect of NBP scenarios for changes in farming intensity (varying chemical fertilizer and manure application rates), land cover change (agriculture vs forest) and nutrient loss mitigation (buffer strips and wetlands) in the River Odense catchment. Subsequently, the NBPs were combined with medium (RCP4.5) and strong (RCP8.5) climate change scenarios for the period 2041–2070 utilising the median of an ensemble of 20 and 57 climate models, respectively. Our study clearly showed that only one of the pathways, namely NBP1 (sustainability first), would enable catchment managers to fulfil the Water Framework Directive reduction target set for the total nitrogen loads in the River Odense catchment by reducing total nitrogen loads by 66%. One of the pathways (NBP5; growth first) caused an increase in the average annual total nitrogen loads by 12%, while the NBP3 scenario (self-sufficiency) reduced the total nitrogen loads with 18% compared to 2% in the case of NBP2 (business as usual) and 29 % for NBP4 (cities first). Surprisingly, climate change had only limited added impacts on the total nitrogen loads due to increased nitrogen uptake of crops. Our study provides policy makers with information on the influence of the different choices and directions taken towards transforming societies into bio-economies in the future.