Promotion of phosphate release from humic acid-iron hydroxide coprecipitates in the presence of citric acid

Phosphate (P) resources are expected to be depleted within a century. Therefore, promoting balanced phosphorus fertilizer use and understanding phosphorus dynamics in soils containing iron (III), organic acids, and iron (III)-organic molecule particulates is crucial. This study investigated the sorption of citric acid onto humic acid-iron hydr(o)xide coprecipitate (HAFHCP) and the reciprocal effects of citric acid and P sorption on HAFHCP with different C/Fe ratios. The results showed that the maximum sorption capacity (MSC) of citric acid on HAFHCP decreased with increasing C/Fe ratios in the HAFHCP. The P sorption on HAFHCP pre-sorbed with citric acids (denoted as C-P) decreased by 50% compared with that of the MSC on FH. However, citric acids could only reduce P sorption by 20% when P was pre-sorbed on HAFHCP (denoted as P-C). The results suggested that upon the formation of HAFHCP, citric acids might increase P availability, especially in the C-P system. Although citric acids initially inhibited P sorption on HAFHCP in the P-C system, P sorption increased with prolonged reaction time. The exposures of new sorption sites upon dissolution of Fe from HAFHCP by citric acids or/and the formations of Fe bridge between P and organic domains of HAFHCP might contribute to these results. Additionally, a number of large HAFHCP aggregates became smaller while sorbing P due to the increasing electric repulsion on the surfaces of FH, enabling the subsequent dissolutions of more Fe by citric acids from HAFHCP in the P-C system. By integrating these innovative and sustainable strategies, the recycling and reuse of P can be optimized, thereby minimizing the reliance on synthetic fertilizers and mitigating environmental impacts. This approach fosters the efficient utilization of phosphorus resources, improves soil fertility, and enhances the overall resilience of agricultural systems and ecosystems.

Metabolic maturation in the first 2 years of life in resource-constrained settings and its association with postnatal growths

Malnutrition continues to affect the growth and development of millions of children worldwide, and chronic undernutrition has proven to be largely refractory to interventions. Improved understanding of metabolic development in infancy and how it differs in growth-constrained children may provide insights to inform more timely, targeted, and effective interventions. Here, the metabolome of healthy infants was compared to that of growth-constrained infants from three continents over the first 2 years of life to identify metabolic signatures of aging. Predictive models demonstrated that growth-constrained children lag in their metabolic maturity relative to their healthier peers and that metabolic maturity can predict growth 6 months into the future. Our results provide a metabolic framework from which future nutritional programs may be more precisely constructed and evaluated.

Energy supply to livestock from tropical rangeland during the dry season

Nine key forage species (grasses and legumes), together with two types of crop residues, usually fed by farmers to their livestock, were collected from a rainfed area in western Sudan during the dry season (May-April). The grasses investigated were Leptadena pyrotechnia, Cenchrus setigrus, Arista pallida, Eragrotis tremula, Schoenefeldia gracilis, Chloris vergata and Cenchrus biflorus. The crop residues investigated were the grasses, sorghum straw (Sorghum bichlor) and millet straw (Pennisetum typhodium) and the legumes Stylosanthes flavicans and Cajanus cajana. Estimates of organic matter (OM) degradability were done using the nylon bag technique, which was fitted into the model Y = a + b (1 - e(-ct)), in which the asymptote (a + b) represented the total potential degradability. Organic cell wall constituents and hence both metabolizable energy and total digestible energy or nutrients (TDN) were determined. S. flavicans showed the best organic matter degradability, and sorghum straw was better degraded than millet straw. The rest of the grasses showed poor OM degradability. Acid detergent insoluble nitrogen was inversely related to TDN, the latter falling within a narrow range for the different forages. Fermentable metabolizable energy differed only slightly, while the legume S. flavicans had the highest effective rumen digestible protein. Undegraded proteins were high for the straws and the grasses L. pyrotechnia and C. setigerus. Metabolizable protein and microbial protein were highest in the sorghum straw, C. setigerus and S. flavicans.

A possible association between dietary intake of copper, zinc and phosphate and delayed puberty in heifers in Sudan

Zinc and copper deficiencies have been reported in heifers of various breeds at four different locations in Sudan. These were Kuku (5 km north of Khartoum), Seleit (20 km northwest of Khartoum), Medani (180 km south of Khartoum) and El Obeid (600 km west of Khartoum). Phosphorus deficiency was only observed in the serum of heifers at El Obeid. The heifers at all locations showed delayed puberty, stunted growth and infertility. The heifers of the local breeds at El Obeid only attained puberty by 1530 days of age compared with 840 days for the pure Friesian heifers at Seleit. The crossbred animals at Kuku and Medani attained puberty at 1440 and 1020 days of age, respectively. The marginal or low zinc and copper contents in pasture, soil or animal feed may have been predisposing factors for the observed deficiencies and might have been responsible for the delayed age of puberty.