Drinking water treatment residuals can be beneficially used to reduce phosphorus (P) in runoff water from manured agricultural land. The objective of this study was to determine treatment residual components responsible for P sorption and reduction of P in runoff water. Using 21 aluminum‐ (Al‐) based treatment residuals from Oklahoma utilities, chemical components related to P sorption (amorphous Al [Alox, 1.33–48.7 g/kg], iron [Fe] [Feox, 0.23–7.44 g/kg] oxides), clay (0–100%), and water‐soluble calcium (0.05–0.74 g/kg) were measured. Linearized Langmuir P sorption maxima (Pmax) ranged from 0.30 to 5.14 g/kg, and nonlinear Freundlich P distribution coefficient (KP) ranged from 17.5 to 1,085 L/kg. Addition of water treatment residuals (50 Mg/ha) to box plots treated with poultry litter (16.7 Mg/ha) reduced runoff P by from 14.0 to 84.9%. Reductions in runoff P were strongly correlated (p < 0.05) with Pmax and Alox. Performance of treatment residuals as a P sorbent to reduce runoff P from manured land can be estimated from their Pmax or Alox content.

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The biosphere, our fragile and exquisite home, is changing abruptly and irrevocably, largely from human interference. Most or all of the coming stresses have links to the land, so finding hopeful outcomes depend on wide and deep understanding of soils. In this review, we pose eight urgent issues confronting humanity in coming decades: demands for food, water, nutrients, and energy; and challenges of climate change, biodiversity, “waste” reuse, and global equity. We then suggest some steps soil scientists might take to address these questions: a refocusing of research, a broadening of vision, a renewed enticement of emerging scientists, and more lucid telling of past successes and future prospects. The questions posed and responses posited are incomplete and not yet fully refined. But the conversations they elicit may help direct soil science toward greater relevance in preserving our fragile home on this changing planet.

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Micronucrient availability is important to crop production and can be affected by long-term application of P and organic amendments. This study was condutted to determine the effects ofthe long-term application of different sources and rates of P application on extracrable [DTPA-sorbitol (diethylenetriamine-pentaacetic acid and sorbitol] micronutrients. Soil extractable and total micronutrients (B, Cu, Fe, Mn, Mo, and Zn), pH, and organic matter content were determined from sites across Oklahoma that had received long-term applications of beet manure, swine effluent, biosolids, or commercial fertilizer. Three continuous inorganic P experiments diat had been conducted for 36 to 39 yr and three organic P experiments diat had been conducted for 11 to 12 yr were evaluated. Tlie long-term application of inorganic P had litde effect on micronutrient availability. However, long-term application of biosolids significandy {p < 0.05) increased extractable Cu, Fe, Mo, and Zn in soil, while long-term application of beef manure significandy increased all die micronutrients evaluated. Similarly, the long-term application of swine effluent significantly increased extractable B, Cu. Mo, and Zn in soil. The addition of micronutrients from organic amendments increased micronutrient availability, while long-term inorganic P application had litde effect. The result of our study indicates organic amendments make an ideal fertilizer source for areas with micronutrient deficiencies.Abbreviations: DTPA, diethylenetriamine-pentaacetic acid; EDTA, ethylenediamine-tctraacetic acid; ICP-AES, inductively coupled plasma atomic emission spectroscopy; SOM, soil organic matter; TSP, triple superphosphate.