Phosphorus Availability in Lolium perenne L. in Acidic and Limed Soils

Soil liming may increase phosphorus (P) availability, but this increase may also be achieved with generous P applications. However, it is not well known which practice has longer-term effects. Thus, in a pot experiment, an acidic soil (pH 4.57), limed to pH 6.5, was added with P and sown with Lolium perenne L. We conducted three cuttings (on Days 40, 80, and 120) in order to evaluate P dynamics in each of the treatments. As expected, biomass increased significantly with liming. We also found that plant P concentration increased in the liming treatment, but not in the P-added treatment, although the difference was reduced on Day 120. This shows that in severely acidic soils, liming should be preferred over P addition, although the beneficial effects may not last for a very long time, since in this experiment, they only lasted for 4 months. Similar conclusions were drawn from soil P extraction results. © 2017 Taylor & Francis

Nitrogen, Phosphorus, and Potassium Availability in Manure- and Sewage Sludge-Applied Soil

A field experiment with wheat (Triticum aestivum L.) was established over two growing seasons where farmyard manure and sewage sludge, along with conventional fertilizer, were added to soil. We found that ammonium N was at greater concentrations in the organic amendments treatments, indicating more beneficial dynamics (i.e., it can be taken up by plants for a greater amount of time) and thus a longer lasting effect as a nutrient for the test crop. We found that nitrogen (N), phosphorus (P), and potassium (K) uptake increased with added organic amendments. This means that when organic matter along with nutrients are added to soil, productivity may increase beyond preset targets because soil conditions greatly improve, not only chemically but also physically. Nitrates left over at the end of the growing season (residual N) were greater in the high sewage sludge and manure treatments, but not proportionally

Nitrogen and phosphorus availability to ryegrass in an acidic and limed zeolite-amended soil

Nitrogen and P fertilization increases crop yields, especially in acidic soils, but its effect may be minimized by various N loss and P retention processes. Zeolite may enhance N and P fertilizer efficiency. The aim of this study was to compare N and P availability and recovery efficiencies to ryegrass, as well as soil available nitrogen, in acidic and limed zeolite-added soils. In a pot experiment with ryegrass we added escalating zeolite quantities to an acidic and limed soil and we measured soil NH4-N dynamics and N and P in plant. Added zeolite protected NH4-N by releasing it more slowly when compared to the no-zeolite treatments. Recovery efficiency (uptake compared to added nutrient) increased with zeolite from 11.7% (no-zeolite) to 30% (zeolite treatment) for N and from 1.52% to 4.02% for P. Even under the unfavourable conditions of an acidic soil, N and P recovery efficiencies were greatly improved due to zeolite. This was induced by the slow release of ammonium cations, which kept the available NH4-N unchanged and due to the protection of the available P from being retained onto soil colloids

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

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