Sunflower growth and yield response to sewage sludge application under contrasting water availability conditions

Good knowledge of crop response to biosolids is necessary for optimizing their use as soil amendments. The present 2-yr study evaluated the impact of soil application of municipal sewage sludge on growth, dry matter translocation, achene and oil yield as well as on achene Fe, Cu, Zn and Mn content of field-grown sunflower (Helianthus annuus L.) under contrasting water availability in terms of seasonal rainfall. Treatments included three sewage sludge rates (9, 18, and 36 Mg dry weight ha−1 yr−1) compared with inorganic fertilizer (138 kg N plus 24 kg P ha−1 yr−1) and a non-amended control. Adding sewage sludge increased stem diameter, height, and early growth of sunflower plants compared with control. Dry matter at flowering was positively correlated with translocation of dry matter to achenes (r = 0.855**). However, high early dry matter was translated into enhanced achene yield only with adequate water availability along growth cycle, while water shortage resulted in fewer achenes and poor seed-filling. Sewage sludge application increased achene yield even under water shortage, suggesting a beneficial effect of sewage sludge on soil water status. Achene yield with added sewage sludge was similar to or greater than with the inorganic fertilizer. Sewage sludge decreased achene oil concentration and increased achene N concentration, compared with the non-amended control, without affecting Zn, Fe, Mn, and Cu content in achenes even at the high application rate of 18 Mg ha−1. Findings support that sewage sludge addition in soil at the rate of 9 Mg ha−1 was agronomically adequate and could replace inorganic fertilizer in sunflower production, irrespective of seasonal rainfall amount and distribution patterns. © 2020 Elsevier B.V

Sewage Sludge Influences Nitrogen Uptake, Translocation, and Use Efficiency in Sunflower

A better understanding of crop and soil response to biosolids is necessary for optimizing their use as soil amendments. The present study examined the influence of sewage sludge application on N accumulation, partitioning, translocation, and N use in sunflower and on soil properties compared with mineral fertilizers. Treatments included the application of sewage sludge (9, 18, and 36 Mg dry weight ha−1 year−1), an inorganic fertilizer (138 kg N plus 55 kg P2O5 ha−1 year−1), and a non-amended control. Sewage sludge increased early crop growth rate and N uptake at levels similar to or even greater than those obtained with the inorganic fertilizer. Nitrogen translocation was correlated with nitrogen translocation efficiency (r = 0.66*); both parameters appeared to be associated with source and sink attributes. Nitrogen use efficiency and nitrogen uptake efficiency were decreased with increasing rates of sewage sludge following a quadratic response curve. The estimated nitrogen use efficiency of sewage sludge-added N was greater than that of the inorganic fertilizer when sewage sludge was applied at agronomically realistic rates (< 26 Mg ha−1 in the first year or < 18 Mg ha−1 in the second year). Sewage sludge application increased soil organic matter and Olsen P compared with the control. Soil electrical conductivity in sewage sludge treatments remained at acceptable levels and soil concentrations of DTPA-extractable trace elements were similar to those of the control or the inorganic fertilizer. In the light of these findings, treated municipal sewage sludge may be used in sunflower intended for biodiesel production replacing mineral fertilizers serving as alternative sewage sludge disposal method. © 2020, Sociedad Chilena de la Ciencia del Suelo

Effect of organic manure on wheat grain yield, nutrient accumulation, and translocation

A field study was conducted for two consecutive growing seasons to assess the effect of organic manure on the growth, productivity and nutrient dynamics of winter wheat (Triticum aestivum L.), as well as on the concentration of trace elements in soil and wheat plants. Treatments consisted of two rates of farmyard manure (16 and 32 Mg dry weight ha−1 yr−1), one rate of inorganic fertilizer (IF, 120 kg N ha−1 yr−1 plus 80 kg P2O5 ha−1 yr−1), and an unamended control. Manure improved wheat growth and productivity compared to the unamended control; the response was dependent on the application rate. The high manure rate increased the number of spikes m−2 and resulted in grain yield similar to that of the IF. Manure application caused no changes in N, P, and K concentrations in plant tissues. At the high manure rate, N and P uptake was similar to that of the IF. Averaged across years, manure application resulted in nutrient translocation from vegetative parts to grain at a lower (for the N) or similar (for the P) rate to that of the IF. No differences among treatments in nutrient translocation efficiency were observed. Nitrogen and P translocation was correlated with total aboveground N or P accumulation at anthesis, respectively. The N use efficiency of manure-N was lower compared with that of inorganic fertilizer-N, mainly because of the corresponding differences in uptake efficiency. Trace elements did not increase with added manure either in soil or in wheat plant tissues. © 2016 by the American Society of Agronomy 5585 Guilford Road, Madison, WI 53711 USA. All rights reserved

Environmental impact of rice production based on nitrogen fertilizer use

While essential to food production, nitrogen (N) fertilizers in agricultural ecosystems are also important sources of environmental pollution nationally and globally. The environmental impact of three N fertilization levels (30, 60, and 90\ua0kg\ua0ha-1) plus a non-N control (0\ua0kg\ua0ha-1) in growing three rice cultivars (cv. Hashemi, cv. Alikazemi, and cv. Khazar) were assessed for 2\ua0years in northern Iran, with the methodology of the life cycle assessment (LCA). The impact categories evaluated in this study were global warming, acidification, terrestrial eutrophication, and depletion of fossil, phosphate, and potassium resources. Over cultivars, no use of N fertilizer provided the lowest grain yield (2194\ua0kg\ua0ha-1), whereas the N rates of 60 and 90\ua0kg\ua0ha-1increased grain yield by 52.9 and 66.9%, respectively. Over N rates, cv. Khazar produced the highest grain yield (3415\ua0kg\ua0ha-1) and cv. Hashemi the lowest (2663\ua0kg\ua0ha-1). On-farm (foreground) emissions were higher than off-farm (background) emissions in most impact categories. The maximum value of environmental index (1.33) was observed for cv. Hashemi with 90\ua0kg\ua0N\ua0ha-1, while the minimum value (0.38) was observed for cv. Khazar without N fertilization. Moreover, cv. Khazar showed the lowest resource depletion index (0.44) with 90\ua0kg\ua0N\ua0ha-1, whereas cv. Hashemi with no use of N showed the maximum value (0.96). Over cultivars, high N rates imposed drastic impact to the categories acidification and terrestrial eutrophication. However, selection of high-yielding cultivars significantly alleviated the impact to most categories. Fertilization that enables optimal yields, in accordance with the nutrient requirements of crops, ensures the most efficient land use and sustainable rice production

Multiple resistance of silky windgrass to acetolactate synthase-and acetyl-CoA synthase-inhibiting herbicides

Field and pot experiments were conducted in Greece to study the occurrence of resistance in silky windgrass to acetolactate synthase (ALS)-and acetyl-CoA synthase (ACCase)-inhibiting herbicides. Twenty-four populations of silky windgrass were examined in whole-plant response experiments. High levels of field-evolved resistance to chlorsulfuron (0% to 28% control in terms of fresh weight reduction) with the recommended field rates were confirmed in most silky windgrass populations. However, other ALS inhibitors, such as pyroxsulam and a premix of mesosulfuron-methyl and iodosulfuron, provided adequate control (76% to 100% in terms of fresh weight reduction) of most populations, except eight silky windgrass populations that were found to be cross-resistant to all ALS-inhibiting herbicides tested (i.e., chlorsulfuron, commercial mixture of mesosulfuron-methyl plus iodosulfuron, and pyroxsulam). Conversely, most silky windgrass populations were controlled effectively (90% to 100% in terms of fresh weight reduction) with the recommended field rates of ACCase inhibitors cycloxydim, clethodim, and pinoxaden, but five populations were also found to be resistant to clodinafop-propargyl (10% to 68% control in terms of fresh weight reduction). The ALS gene sequencing of the eight silky windgrass populations, with cross-resistance to ALS inhibitors, revealed a point mutation at the Pro-197 position, causing amino acid substitution by Ser or Thr in the ALS enzyme. Overall, chlorsulfuron and clodinafop-propargyl were selecting agents of field-evolved multiple resistance to ALS-and ACCase-inhibiting herbicides in five silky windgrass populations. As the available postemergence-applied chemistries/modes of action registered for grass weed control in cereals are rather limited, adopting integrated management practices and implementing proactive and reactive measures to delay the evolution of resistant populations is essential.