Chemically Precipitated Struvite Dissolution Dynamics over Time in Various Soil Textures

Phosphorus (P) is a fundamental nutrient in agricultural production and is one of three major components in common fertilizers. The majority of fertilizer-P sources are derived from phosphorus rock (PR), which has finite abundance;thus a sustainable source of P is imperative for future agricultural productivity. A potential sustainable P source may be the recovery of the mineral struvite (MgNH4PO4·6H2O) from wastewater treatment plant effluent, but struvite behavior in soils of varying texture is not well characterized. The objective of this study was to assess the dissolution dynamics of a commercially available, wastewater-recovered struvite product over time in a plant-less, moist-soil incubation experiment with multiple soil textures. Chemically precipitated struvite (Crystal Green;CG) from municipal wastewater in pelletized and finely ground forms were added to soil cups at a rate of 24.5 kg∙P∙ha−1 containing soils of varying texture (i.e. loam, silty clay loam, and two different silt loams) from agricultural field sites in Arkansas. Soil cups were destructively sampled five times over a 6-month period to examine the change in water-soluble (WS) and weak-acid-extractable (WAE) P, K, Ca, Mg, and Fe concentrations from their initial concentration. After 0.5 months, both WS-P and WAE-P concentrations increased (P < 0.05) more from initial concentrations of the finely ground CG in all soils, which averaged 76.2 and 158 mg∙kg−1, respectively, than in the pelletized CG treatment, which averaged 14.0 and 12.2 mg∙kg−1, respectively, across all soils. Over the course of the 6-month incubation, WS- and WAE-P concentrations generally increased over time in the pelletized and decreased over time in the finely ground treatment, confirming the slow-release property of pelletized CG that has been previously reported. The results of this study provide valuable insight regarding struvite-P behavior in various soils and provide further supporting evidence for the utilization of struvite as a potential alternative, sustainable fertilizer-P source.

Division of domestic labor and fertility behaviors in China:the impact of extended family traditions on gender equity theory

Gender equity in division of domestic labor and its positive effects on fertility have been well documented in Western countries.This research extends the classic gen-der equity theory to East Asia,a country with an extended family tradition that complicates gender roles.Using four waves of data from the China Family Panel Study(CFPS),we find that:(1)parents or parents-in-law serve as a major source of informal help for housework and childcare in China;(2)the domestic help from parents can significantly increase the likelihood of childbearing for Chinese women;(3)the help from husbands is less important and only significant when parental help is absent.While gender equity in the West has a profound influence on gender equity in the East,Confucian traditions that assign roles according to gender and to the relationships among grandparents,parents,and children are a force to be reckoned with in China.