Crop Uptake Research Articles

Chemicals/materials of emerging concern in farmlands: sources, crop uptake and potential human health risks.

Certain chemicals/materials that are contaminants of emerging concern (CECs) have been widely detected in water bodies and terrestrial systems worldwide while other CECs occur at undetectable concentrations. The primary sources of CECs in farmlands are agricultural inputs, such as wastewater, biosolids, sewage sludge, and agricultural mulching films. The percent increase in cropland area during 1950-2016 was 30 and the rise in land use for food crops during 1960-2018 was 100-500%, implying that there could be a significant CEC burden in farmlands in the future. In fact, the alarming concentrations (μg kg-1) of certain CECs such as PBDEs, PAEs, and PFOS that occur in farmlands are 383, 35 400 and 483, respectively. Also, metal nanoparticles are reported even at the mg kg-1 level. Chronic root accumulation followed by translocation of CECs into plants results in their detectable concentrations in the final plant produce. Thus, there is a continuous flow of CECs from farmlands to agricultural produce, causing a serious threat to the terrestrial food chain. Consequently, CECs find their way to the human body directly through CEC-laden plant produce or indirectly via the meat of grazing animals. Thus, human health could be at the most critical risk since several CECs have been shown to cause cancers, disruption of endocrine and cognitive systems, maternal-foetal transfer, neurotoxicity, and genotoxicity. Overall, this comprehensive review provides updated information on contamination of chemicals/materials of concern in farmlands globally, sources for their entry, uptake by crop plants, and their likely impact on the terrestrial food chain and human health.

Long-term fertility experiments for irrigated rice in the West African Sahel: Effect on macro- and micronutrient concentrations in plant and soil

Little is known about the impact of long-term intensive irrigated rice cropping on secondary macro and micronutrients in soils and crops. Therefore, the present study analysed the effect of intensive irrigated rice cropping on nutrient concentrations in soils and rice (grain and straw at harvest) in two long-term experiments that were established in 1991 for intensive rice-based irrigated systems in the Senegal River valley at Ndiaye and Fanaye, Senegal. The experiments included six different fertilizer treatments and rice was grown for two seasons per year. The samples were collected in the 2016/17 dry season (26 years or 52nd continuous rice cropping season after the establishment). Average grain yields from 1991 to 2016/17 for the different fertilizer treatments indicate that yield was limited by N and P at both sites. At Ndiaye, 120 kg N ha −1 seemed sufficient to reach highest achievable yields, whereas 180 kg N ha −1 was necessary at Fanaye. Soil organic carbon and total soil N did increase considerably over the full length of the experiment at both sites and in all treatments even though all crop residues were removed every season. The estimated increase in total topsoil N (across all fertilizer treatments) per season was 10.8 and 11.4 kg N ha −1 at Ndiaye and Fanaye, respectively. Fertilizer treatments differed in their N, P and K rate but significant effects on total soil concentrations were only detected for P. Using the Mehlich3 soil test, we analysed treatment effects on available P, K, Ca, Mg, S, Mn, Zn and Fe. Critical Mehlich3 values from the literature indicated likely P limitation at both sites and in all but one treatment (high PK treatment), a starting but minor K limitation at Fanaye, a strong S limitation at Fanaye, and a minor Zn limitation at Fanaye and Ndiaye. These indications were mostly confirmed by the grain and straw analysis but with the exception of the P limitation, the actual effect of these possible nutrient limitations on production would need to be tested with targeted field experiments. We conclude that continuous rice cultivation in the Sahel for 26 years can be sustained and even increases soil organic carbon and total soil nitrogen. However, in addition to the common N and P deficiencies, likely deficiencies of K, S and Zn are appearing and may begin to limit rice yields in intensive systems in Africa. The Mehlich3 test seems an efficient tool to identify such deficiencies in irrigated rice soils. • 26 years of continuous rice cultivation increased SOC and total soil N significantly • System N losses are therefore over-estimated when based on crop uptake only • Fertilizer application effects on total soil concentrations were only detected for P • The Mehlich3 method indicated possible upcoming limitations from K, S and Zn

Estimation of fluoride uptake in soil and staple food crops produced in highly fluoridated and non-fluoridated regions of Raichur District, Karnataka.

A staple food crops have varied role in diet of people living in particular regions of world; hence, it is critical to recognize their productivity. Therefore, the purpose of this study was to estimate fluoride concentration in staple food crops grown in highly fluoridated and non-fluoridated regions and its correlation with soil. Total 36 samples were collected of which 18 samples consisting of each three samples of rice, redgram and jowar were selected. Likewise 18 corresponding soil samples from both areas were collected. All samples were ashed for 4-6 hours at 550°C in muffle furnace. The samples were allowed to cool, after which 10 ml distilled water was added to each sample and fluoride concentration was determined using ion selective electrode method, before each sample analysis the instrument was standardized using fluoride containing TISAB (III) buffer solution. The data was tabulated and subjected to cross-sectional observational statistical analysis using SPSS software applying unpaired t-test and Pearson's test. The mean fluoride concentration in crops and soils were rice (0.79 ppm), redgram (4.26 ppm), jowar (8.8 ppm) and in soil of rice (1.23 ppm), redgram (1.23 ppm) and jowar (1.21 ppm) respectively in fluoridated area. Where as in non-fluoridated area rice (0.07 ppm), redgram (0.81 ppm), jowar (0.81 ppm) and in soil of rice (0.61 ppm), redgram (0.07 ppm) and jowar (0.52 ppm) respectively. The resultant correlation between staple food crops with their corresponding soils were found highly significant in both regions with P value <0.005; hence, crops in fluoridated region exhibited increased fluoride retention, whereas crops in non-fluoridated region had optimal fluoride levels. Fluoride concentration in food crops has strong correlation with their respective soils and water irrigation properties.

Effect of potassium and zinc application on crop yield and uptake of nutrients in green gram (Vigna radiata L.) under coarse textured soils

The aim of present study was to find out the optimum dose and application effect of potassium (K) and zinc (Zn) on green gram yield, nodulation, uptake and its build-up/depletion in soil to overcome the production of pulses in Haryana. A series of field experiments were conducted during kharif season from 2018 to 2020 at the Regional Research Station, Chaudhary Charan Singh Haryana Agricultural University (CCSHAU), Bawal, Haryana. The experiment was laid out in a split plot design with four levels of K (0, 10, 20 and 30 kg K2O ha−1) in main plot and Zn (0, 12.5, 25 and 37.5 kg ZnSO4 ha−1) in sub-plot with three replications. The results revealed that application of K significantly affected the yield of green gram up to 20 kg K2O ha−1 whereas Zn application significantly affected the yield of green gram up to 25 kg ZnSO4 ha−1. The interaction between K and Zn was non-significant. The nodules fresh weight and number of nodules per plant increased significantly with the application K whereas, these parameters increased with the application of Zn but results were not significant. The K and Zn application significantly increased their content and uptake in seed and straw of green gram. The available K in soil was influenced by K application but was found to be significant with 20 and 30 kg K2O ha−1. The DTPA extractable Zn content in soil after harvest of crop was also significantly higher with the application of zinc sulphate.

Timing of potassium chloride application effect on soil and potato uptake of chloride

AbstractPotassium chloride (KCl) is often used to supply K for potato (Solanum tuberosum L.) production; it is the least costly K fertilizer. However, crop uptake of Cl can reduce diagnostic petiole NO3–N and reduce tuber specific gravity. This trial evaluated the effect of K fertilizer source (KCl vs. sulfate of potash [SOP] and sulfate of potash magnesia [KMag]) and fertilizer application timing on Cl, S, N, and K in soil, petioles, and whole plant biomass. Fertilizers were applied at 224 kg K2O ha–1 at three application timings: 210 d before planting (fall preplant), 14 d before planting (spring preplant), or 35 d after planting (Layby) to a sandy loam soil in Hermiston, OR. Nitrogen fertilizer was applied by overhead sprinklers during the growing season. Potassium source and timing had minimal effect on crop S, N, and K uptake. Crop Cl response reflected a fertilizer source × timing interaction. Fall‐applied KCl did not increase plant Cl above that observed for KMag and SOP treatments. Spring or summer‐applied KCl increased plant Cl concentrations. The most likely explanation for this response pattern was leaching of Cl below rooting depth with fall fertilizer application. Findings of importance for potato production practices in our region included: (a) fall‐applied Cl was not taken up by the crop, and so did not represent a risk to potato tuber quality; (b) elevated concentrations of petiole Cl from preplant or in‐season KCl application did not affect petiole NO3–N.

Risks for Using FeCl3 Under a Submerged Condition, and Different Water Management to Reduce Uptake of Antimony and Cadmium in a Rice Plant

Soil pollution by multiple metal(loid)s is a common problem, and it is not easy to synchronously reduce their uptake in crops. Compounds containing iron (Fe) are often used to efficiently remediate soil metal(loid) pollution; however, its associated risks did not receive much attention especially under unsuitable soil water conditions. Pot experiments were set up using an antimony (Sb) and cadmium (Cd) co-contaminated soil treated with a continued submergence condition plus 5, 10, or 20 mg kg−1 FeCl3 (Experiment I), or treated with different water management including submergence, intermittent irrigation, and dry farming (Experiment II). Our results showed that the continued submergence resulted in excessive accumulation of arsenic (As) in different tissues of rice plants even if the soil As background concentration is low. High soil moisture content increased the available concentrations of Sb and As, but reduced that of Cd in rhizosphere soils, which was in line with their concentrations in different tissues of rice plants (Experiment II). Under a continued submergence condition, FeCl3 significantly stimulated As concentration in the shoots, roots (excluded Fe20 treatment), and husks, but reduced it in the grains. FeCl3 reduced Sb concentration only in the roots and grains, and reduced Cd concentration only in the husks, suggesting a limited efficiency of FeCl3 to reduce Cd uptake under a submergence condition. In this study, the dynamic changes of As, Sb, and Cd concentrations in soil solution, their available concentrations in rhizosphere soils, their accumulation in root iron/manganese plaques, and the relationships among the above parameters were also discussed. We suggested that if FeCl3 would be used to remediate the contaminated soils by Sb and Cd, dry farming for a short time is needed to avoid As accumulation, and intermittent irrigation is a potential choice to avoid the excessive accumulation of As, Sb, and Cd in the edible parts of rice plants.

Cadmium Speciation Distribution Responses to Soil Properties and Soil Microbes of Plow Layer and Plow Pan Soils in Cadmium-Contaminated Paddy Fields.

Cadmium (Cd) speciation ratio in arable land determines the Cd exposure risk and Cd uptake in crops. However, the driving mechanisms of Cd speciation change on the vertical scale of paddy fields remain poorly understood. In this study, the effects of plow layer and plow pan on Cd speciation distribution were investigated in a long-term Cd-contaminated rice ecosystem. The Cd accumulative effect within rice grain was enhanced with high levels of activated Cd speciation ratios in soils. Activated Cd speciation ratios were higher in plow layer soils, while stabilized Cd speciation ratios were elevated in plow pan soils. Soil physicochemical properties and soil microbes synergistically affected the Cd speciation changes in different ways between the two soil layers. Soil pH and organic elements in plow layer environment directly hindered the transformation of stabilized Cd speciation, while in plow pan environment, soil pH and organic elements indirectly decreased activated Cd speciation ratios and resulted in the accumulation of stabilized Cd speciation via regulating the predominant bacterial taxa. This study will improve our understanding of how soil environments regulate Cd speciation distributions in rice ecosystems and help to seek effective remediation methods of Cd-contaminated paddy fields to reduce the Cd accumulation in rice.

Mycorrhizal fungi-mediated uptake of tree-derived nitrogen by maize in smallholder farms

Trees within farmers’ fields can enhance systems’ longer-term productivity, for example, via nutrient amelioration, which is indispensable to attain sustainable agroecosystems. While arbuscular mycorrhizal fungi (AMF) are known to improve plant access to soil nutrients, the potential of AMF to mediate nutrient uptake of tree-derived nitrogen (N) by crops from beyond the crops’ rooting zones is unclear. We hypothesized that AMF quantitatively contribute to the crop uptake of tree-derived N. We set up root- and AMF-exclusion and control plots around faidherbia trees (Faidherbia albida) and used the 15N natural abundance technique to determine the magnitude of AMF-mediated uptake of tree-derived N by maize from beyond its rooting zone in smallholder fields. We further tested whether AMF-mediated N uptake decreases with distance from tree. We show that within one cropping season, maize obtained approximately 35 kg ha–1 biologically fixed N from faidherbia. One-third of tree-derived N in maize leaves was attributed to AMF-mediated N uptake from beyond the maize rooting zone and two-thirds to N from tree leaf litter, regardless of distance from tree. As hypothesized, maize grown close (1 m) to faidherbia obtained significantly more tree-derived N than that at farther distances (4 and 5 m). Thus, the faidherbia–AMF association can enhance agroecosystem functioning.

Agricultural phosphorus surplus trajectories for Ontario, Canada (1961–2016), and erosional export risk

Management strategies aimed at reducing nutrient enrichment of surface waters may be hampered by nutrient legacies that have accumulated in the landscape. Here, we apply the Net Anthropogenic Phosphorus Input (NAPI) model to reconstruct the historical phosphorus (P) input trajectories for the province of Ontario, which encompasses the Canadian portion of the drainage basin of the Laurentian Great Lakes (LGL). NAPI considers P inputs from detergent, human and livestock waste, fertilizer inputs, and P outputs by crop uptake. During the entire time period considered, from 1961 to 2016, Ontario experienced positive annual NAPI values. Despite a generally downward NAPI trend since the late 1970s, the lower LGL, especially Lake Erie, continue to be plagued by algal blooms. When comparing NAPI results and river monitoring data for the period 2003 to 2013, P discharged by Canadian rivers into Lake Erie only accounts for 12.5% of the NAPI supplied to the watersheds' agricultural areas. Thus, over 85% of the agricultural NAPI is retained in the watersheds where it contributes to a growing P legacy, primarily as soil P. The slow release of legacy P therefore represents a long-term risk to the recovery of the lake. To help mitigate this risk, we present a methodology to spatially map out the source areas with the greatest potential of erosional export of legacy soil P to surface waters. These areas should be prioritized in soil conservation efforts.

The Effect of Meat and Bone Meal (MBM) on Crop Yields, Nitrogen Content and Uptake, and Soil Mineral Nitrogen Balance

A long-term (six year) field experiment was conducted in Poland to evaluate the effect of meat and bone meal (MBM), applied without or with mineral nitrogen (N) fertilizer, on crop yields, N content and uptake by plants, and soil mineral N balance. Five treatments were compared: MBM applied at 1.0, 1.5, and 2.0 Mg ha−1, inorganic NPK, and zero-fert check. Mineral N accounted for 100% of the total N rate (158 kg ha−1) in the NPK treatment and 50%, 25%, and 0% in MBM treatments. The yield of silage maize supplied with MBM was comparable with that of plants fertilized with NPK at 74 Mg ha−1 herbage (30% DM) over two years on average. The yields of winter wheat and winter oilseed rape were highest in the NPK treatment (8.9 Mg ha−1 grain and 3.14 Mg ha−1 seeds on average). The addition of 25% and 50% of mineral N to MBM had no influence on the yields of the tested crops. The N content of plants fertilized with MBM was satisfactory (higher than in the zero-fert treatment), and considerable differences were found between years of the study within crop species. Soil mineral N content was determined by N uptake by plants rather than the proportion of mineral N in the total N rate. Nitrogen utilization by plants was highest in the NPK treatment (58%) and in the treatment where mineral N accounted for 50% of the total N rate (48%).

Crop insurance participation and cover crop use: Evidence from Indiana county‐level data

AbstractThis study examines whether crop insurance participation reduces incentives to use cover crops in corn and soybean production. To achieve this objective, we utilize 2006–2015 county‐level longitudinal data with information on cover crop adoption and crop insurance participation for the State of Indiana. Cover crop adoption information is collected from a remote sensing (satellite‐based) data set of soil health practices. Linear fixed effect (FE) models and instrumental variable FE models are used in the empirical analysis to take advantage of the panel nature of the data and address potential endogeneity issues. Our results suggest that while crop insurance coverage may play a role in “disincentivizing” cover crop use, it is likely not a major driver in the cover crop adoption decision (i.e., the magnitude of the effect is small). Therefore, further research and policy attention toward other potential mechanisms that can likely have a larger impact on cover crop uptake may be a better approach (e.g., enhanced outreach programs and/or additional targeted conservation payments).

Study on Integrated Effect of Inorganic Fertilizers and Organic Manure on Available Nutrients, Yield and Nutrient Uptake in Scented Rice

Field experiments were conducted at the Instructional-cum-Research (ICR) Farm, Assam Agricultural University, Jorhat during the year 2017 and 2018 to study the integrated effect of inorganic fertilizers and organic manure on available nutrients, yield and nutrient uptake in scented rice. Before the test crop experiment, fertility gradient experiment was conducted by using kharif rice (cv. Ranjit) as an exhaust crop to create three fertility gradient strips. After harvesting the gradient crop, test crop experiment was conducted in the same field with scented rice (cv. Keteki joha) by superimposing 24 combination treatments consisting of five levels of N (0, 10, 20, 40 and 60 kg ha-1), four levels of P2O5 (0, 5, 10 and 20 kg ha-1), three levels of K2O (0, 10 and 20 kg ha-1) and three levels of vermicompost (0, 2 and 3 t ha-1) in each of these fertility gradient strips. Results show that application of integrated nutrient management approach brought about a positive influence on organic carbon, nutrient availability, crop yield and nutrients uptake by scented rice. Combined application of 60 kg N, 10 kg P2O5 and 10 kg K2O per hectare along with 3 tons of vermicompost per hectare resulted in the highest concentration of available NPK in soils, the highest crop yield and uptake of nitrogen, phosphorus and potassium by rice.

Influence of arbuscular mycorrhizal fungi on selenium uptake by winter wheat depends on the level of selenate spiked in soil

Selenium (Se) deficiency has been a public health concern for years. Arbuscular mycorrhizal fungi (AMF) play an essential role in improving Se uptake in crops, but related mechanisms still remain unclear. To explore the influence of AMF on uptake of Se in winter wheat, a pot experiment was conducted to inoculate wheat with Funneliformis mosseae (F.m) or not under different levels of selenate in soil. The present results indicated that inoculation of F.m significantly (p < 0.05) increased Se concentration in shoots and roots of wheat under low level of selenate (≤5.0 mg kg−1) treatments, while the contrary pattern was recorded under high level of selenate (15 and 20 mg kg−1) treatments. Moreover, inoculation of F.m significantly increased concentration of available Se in soil by 4.68–34.05%. Under selenate ≤5 mg kg−1 treatments, the expression of TaeSultr1;1 and TaeSultr1;3 in roots of mycorrhizal wheat was significantly up-regulated by 3.06–5.53 and 0.63–5.12 times, while reached saturation under selenate >5 mg kg−1 treatments. In addition, partial least squares path modeling (PLS-PM) showed that inoculation of AMF directly affected the expression of sulfate transporter and that both sulfate transporter and soil Se fractions played a significant positive effect on plant Se content. The present study indicated that AMF on Se concentration in winter wheat depends on the level of selenate spiked in soil and added to our understanding of the functions and applications of AMF on crop Se absorption.

Integrative Effects of Treated Wastewater and Synthetic Fertilizers on Productivity, Energy Characteristics, and Elements Uptake of Potential Energy Crops in an Arid Agro-Ecosystem

Using wastewater in agriculture is a desirable alternative source of irrigation and is gaining attraction worldwide. Therefore, this study was designed to assess the effect of treated municipal wastewater (TWW) and groundwater (GW), along with half and full doses of the recommended NPK dose on the plant growth, total biomass, gross energy, and macro- and trace element content and uptake of safflower (Carthamus tinctorius L.), canola (Brassica napus L.), and triticale (X Triticosecale Wittmack) grown in old and virgin soil as potential bioenergy crops. The results showed that crops planted in old or virgin soil irrigated with TWW had higher values of plant height, leaf area per plant, total chlorophyll content, total biomass, and gross and net energy contents compared to those irrigated with GW grown in virgin soil. Similarly, crops grown in old soil irrigated with TWW showed higher concentrations in dry matter and uptake for both macronutrients (N, P, and K) and trace elements (B, Zn, Mn, Cu, Cd, Pb, and Ni) compared to those planted in virgin soil and irrigated with GW. Furthermore, the application of the recommended half dose of NPK in old and virgin soil irrigated with TWW showed occasionally comparable results to that of a full recommended dose of NPK for most of the measured parameters. Importantly, the recommended half dose applied to old soil irrigated with TWW resulted in a significant improvement in all measured parameters compared to virgin soil irrigated with GW, along with a full recommended dose of NPK. Briefly, TWW can be used to irrigate crops grown for bioenergy purposes, since it did not pose any harmful effect for energy crops. In addition, it provides additional nutrients to soil and thus decreases the required rate of synthetic fertilizer by up to 50% without any significant decreases in the final production of crops.

System productivity and economics as influenced by cropping system and nutrient management

A field experiment was conducted during kharif, rabi and summer 2013-16 at ICAR-IARI, New Delhi to study the effect of cropping systems and nutrient management on productivity of different crops and cropping systems, the impact of nutrient management on nutrient uptake in different crops and cropping systems and to evaluate economics of different cropping systems. Experiments were conducted in split-plot design replicated thrice. The treatments were comprised five cropping systems, i.e. pearl millet-wheat, pearl millet-mustard-cowpea, pearl millet-wheat-bottle gourd, clusterbean-mustard-cowpea, and clusterbean-wheat-bottle gourd and four nutrient management, i.e. control, RDN (recommended dose of nitrogen), 50% RDN + 50% N through FYM, and 50% RDN + 50% N through FYM + biofertilizers. All the recommended practices except treatment were adopted. The soil test value based nutrient application was done. Results revealed that maximum pearl millet equivalent yield (13.8 t/ha), production efficiency (37.8 kg/ha/day), rainfall-use efficiency (4.34 kg/ha-mm), net returns (₹89198) and benefit cost ratio (2.55) were found under the cropping system of pearl millet-mustard-cowpea. Total nitrogen uptake was obtained more under pearl millet-wheat-bottle gourd. The nutrient management practice of RDN gave higher pearl millet equivalent yield (13.5 t/ha), production efficiency (37 kg/ha/day), rainfall-use efficiency (4.25 kg/ha-mm), total N uptake (120.2 kg/ ha) and net returns (₹ 80243) but statistically at par with 50% RDN + 50% N-FYM + BF. The highest benefit cost ratio was recorded in 50% RDN + 50% N-FYM + BF (2.07). It is concluded that the cropping system of pearl milletmustard- cowpea with nutrient management practice of 50% RDN + 50% N-FYM + BF produced significantly higher yields and income.

Soil Application of Different Nutrient Levels with Soil Amendment Charred Rice Husk and Seed Treatment of Arbuscular mycorrhizae: Effects on Crop Productivity and Nutrient Uptake on Groundnut (Arachis hypogaea L.)

Background: Different levels of nutrient management practice and soil amendments charred rice husk with Arbuscular mycorrhizae during the critical stages of the crop growth enhances the productivity of the groundnut crop. Methods: The field experiments were conducted summer, kharif and rabi seasons of 2016-17 and 2017-2018 at AC and RI, TNAU, Madurai. The main plots consisted of three levels of irrigation scheduling viz., I1- 0.8 IW/CPE, I2- 0.6 IW/CPE and I3- 0.6 IW/CPE ratio and sub plot comprised of four level of nutrient management practices viz., N1-75% of recommended dose of fertilizer with 5t of charred rice husk, N2- 50% of recommended dose of fertilizer with 5t of charred rice husk, N3-75% of recommended dose of fertilizer with 5t of charred rice husk along with seed treatment of Arbuscular mycorrhiza and N4- 50% of recommended dose of fertilizer with 5t of charred rice husk along with seed treatment Arbuscular mycorrhiza. Result: The study revealed that the highest plant height, dry matter production, leaf area index, leaf single photon avalanche diode value, pod yield and haulm yield, nutrient uptake (N,P,K) of groundnut crop and soil enzyme activities in soil was registered with the application of 75% recommended dose of fertilizer and 5t of charred rice husk as basal with seed treatment of Arbuscular mycorrhiza. The highest pod and haulm yield of 1783, 1935 and 1854 kg ha-1 and 4743, 4272 and 4338 kg ha-1 during summer, kharif and rabi’ 2017 seasons respectively of groundnut was registered with 75% of recommended dose of fertilizer and 5t of charred rice husk as basal with seed treatment of Arbuscular mycorrhiza.

Simultaneous evaluation of kinetic release of labile arsenic and phosphorus in agricultural soils using cerium oxide-based DGT

The adsorption/desorption of arsenic (As) in agricultural soils is of utmost importance for the evaluation of its kinetic release and potential of entering the food chain by uptake of crops. However, the mobility of As in soils is closely related to the migration behavior of soil phosphorus (P) due to their chemical similarity. Here, the distribution and desorption kinetics of As and P in four different types of farmland soils were simultaneously estimated by cerium oxide-based diffusive gradients in thin films technique (CeO2-DGT) coupled with dynamic model of DGT induced fluxes in soils (DIFS). CeO2-DGT was deployed in the soils over 400 h to investigate the interactions between As and P for their migration behaviors. The accumulated masses of As in the DGT devices showed reverse orders with those of P among the four soils, indicating their competitive adsorption on soil solids. The distribution coefficients (Kdl) for the labile As and P derived from the DIFS model were mutually exclusive. Clay in the soil reduced the pool size of the labile As by increasing the irreversible adsorption of As on soil particles. The adsorption rate constants of As were much smaller than P but their desorption rate constants were comparable. Among the four soils, the soil with the highest soil labile As/P molar ratio measured by DGT showed the largest potential of As phytotoxicity. Both As and P could reach the equilibrium of resupply within 0.7– 18 min under DGT depletion, and significant negative correlation was observed between the desorption rate (kb) of As and clay content in the soils.

Nutrient uptake of catch crops under non‐limiting growth conditions

AbstractBackgroundCatch crops enhance nutrient cycling of cropping systems. Considering possible limitations of catch crop studies in field and greenhouse experiments, a new approach was chosen to combine the advantages of both systems in quantifying the potential for nutrient retention by catch crops.AimsThis study aimed at identifying N, P, and K uptake of different catch crop species grown in monoculture and as a mixture under non‐limiting growth conditions in terms of water and nutrient availability.MethodsCatch crops were cultivated under semi‐controlled conditions in large containers (August to November 2020). Shoot N, P, and K uptake, leachate accumulation, and soil Nmin, CAL‐P, and CAL‐K (0–30 cm) were quantified after harvest. After washing, root parameters were quantified with a root scanner.ResultsNutrient uptake of N, P, and K was highest for phacelia. The mixture of seven different catch crops performed equally well. Nutrient uptake was closely related to root length and root surface area.ConclusionsUnder non‐limiting growth conditions, phacelia has the highest potential to conserve N, P, and K for a succeeding crop; however, the low C : N ratio of the frost‐sensitive crop could promote nutrient losses during winter. We conclude that growing a single catch crop can be as effective in reducing the nutrient leaching potential as cultivating a mixture of catch crops when nutrients and water are no growth‐limiting factors.

Cover Crop Effects on Cash Crops in Northern Great Plains No-till Systems Are Annually Variable and Possibly Delayed

ABSTRACT Cover crop adoption in conventional no-tillage corn/soybean production systems has been limited due to the lack of specific information regarding the impact of cover crops on cash crop performance. Within a no-till small grain/cover crop-corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation in eastern South Dakota, we evaluated the impact of fall-planted forage oat (Avena sativa L.), hairy vetch (Vicia villosa Roth), winter canola (Brassica napus L.), and a combination of all three compared to a no cover crop treatment on soil nutrient dynamics, biomass, nutrient uptake, and grain yield of the immediatelyfollowing corn crop. At site-year 1, where cover crop growth was most consistent, corn yield was significantly higher with oat, vetch, and a combination of all three cover crops compared to the no cover crop treatment. At site-year 2, corn yields were equivalent among treatments except the combination treatment which was significantly lower. At site-year 3, corn yields in the canola and oat treatments were equivalent to no cover crop, while corn yields with vetch and the combination treatments were lower. Corn biomass and nutrient uptake responded to treatments similarly to corn yields. For site-years 1 and 2, some cover crop treatments resulted in modest, but significant increases in soil N during spring. For site-year 3, the combination treatment immobilized N during the corn vegetative growth phase but released N during the reproductive phase. Cover crop treatments had little effect on plant-available soil P. However, soybean yields two years following cover crop treatments were higher for all three site years with cover crops compared to no cover crop, with this difference significant in two of the three site-years. Immediate effects of cover crops on the following cash crop under no-till were variable and depend on both fall and spring cover crop biomass, which in turn are dependent on the amount and timing of precipitation and temperature patterns. Cover crops in no-till systems may produce more consistent but possibly delayed benefits by boosting yields of cash crops in later years as cover crop residues decompose.

Integrated Use of Co-Compost with Lignite Fly Ash on Yield and Nutrient Uptake of Certain Crops

A field experiment was conducted to know the response of crops to combined application of co compost and lignite fly ash. Field experiments were conducted in experimental farm (rice and maize) and farmers holding (groundnut and brinjal) to study the response of certain crops to the application of co composts and lignite fly ash grown in clay loam and sandy clay loam soil, respectively. The treatment consisted of Dairy Farm Waste + Crop Residues, Pressmud+ Crop Residues, Dairy Farm Waste + Crop Residues + LFA @5 t ha-1, Dairy Farm Waste + Crop Residues + LFA @10 t ha-1, Dairy Farm Waste + Crop Residues + LFA @15 t ha-1, Pressmud + crop residues + LFA @5 t ha-1, Pressmud + crop residues + LFA @10 t ha-1and Pressmud + crop residues + LFA @15 t ha-1 .The grain and straw yield in rice and maize, pod and haulm yield in groundnut and fruit yield of brinjal were recorded during harvest. Differences in yield of crops between the treatments indicate significantly different effects on soil fertility and crop yield after long-term fertilization. The uptake of nutrients increased linearly with levels of LFA tried and it was higher when it was applied with co compost of pressmud and crop residue. The addition of co composts alone or with graded dose of lignite fly ash significantly improved the physical properties of the soil.