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The persistent environmental relevance of phosphorus (P) and P sorption capacity (PSC) on P loss to surface waters has led to proposals for its inclusion in soil fertility and environmental management programs. As fertility and environmental management decisions are made on a routine basis, the use of laborious P sorption isotherms to quantify PSC is not feasible. Alternatively, pedotransfer functions (pedoTFs) estimate PSC from routinely assessed soil chemical properties. Our objective was to examine the possibility of developing a suitable pedoTF for estimating PSC and to evaluate subsequent PSC‐based indices (P saturation ratio [PSR] and soil P storage capacity [SPSC]) using data from an in‐field laboratory where tile drain effluent is monitored daily. Phosphorus sorption capacity was well predicted by a pedoTF derived from soil aluminum and organic matter (R² =.60). Segmented‐line relationships between PSR and soluble P were observed in both desorption assays (R² =.69) and drainflows (R² =.66) with apparent PSR thresholds in close agreement at 0.21 and 0.24, respectively. Negative SPSC values exhibited linear relationships with increasing soluble P concentrations in both desorption assays and drainflows (R² =.52 and R2 =.53 respectively), whereas positive SPSC values were associated with low SP concentrations. Therefore, PSC‐based indices determined using pedoTFs could estimate the potential for subsurface soluble P losses. Also, we determined that both index thresholds coincided with the critical soil‐test P level for agronomic P sufficiency (22 mg kg−1 Mehlich‐3 P) suggesting that the agronomic threshold could serve as an environmental P threshold. [ABSTRACT FROM AUTHOR]

Little information is available about how grass species and management practices, such as grass clippings management, influence soil C and N accumulation, especially labile soil C. Thus, the objective of this field experiment was to determine the labile soil C, total soil C, soil organic matter (SOM), and total soil N accumulation of Kentucky bluegrass (Poa pratensis L.) and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort. syn. Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh.] cultivars with differing growth rates under different grass clippings management practices. Differences in labile and total soil C occurred between turfgrass species after less than 3 yr of growth post planting: labile soil C was 9.9% higher (851 vs. 774 mg C kg-1 soil), total soil C was 4.2% higher (24.8 vs. 23.8 g C kg-1 soil), and SOM was 8.0% higher (41.7 vs. 38.6 g SOM kg-1 soil) for tall fescue than Kentucky bluegrass. After 2 yr of clippings management treatments, plots where grass clippings were returned had 3.3% more labile soil C (826 vs. 800 mg C kg-1 soil), 3.3% more total soil C (24.7 vs. 23.9 g C kg-1 soil), and 4.6% more total soil N (2.28 vs. 2.18 g N kg-1 soil) than those where clippings were collected. However, grass clippings management did not affect SOM. The results of this study highlight the importance of turfgrass selection and grass clippings management on soil C and N accumulation. [ABSTRACT FROM AUTHOR]

The article presents a study to assess diverse management effects on long-term patterns of nitrate, phosphate and ammonium loads at subsurface drains in the U.S. The management systems being assessed represent common farming practices and theoretically improved systems-level recommendations to reduce edge-field nutrient losses. The study monitored water flow and nutrient concentrations at subsurface drains. Results of the study reveal that fall manuring increases nutrient losses in subsurface-drained cropland and should be discouraged or redefined for improvement.

Investigates the N,N'-dibutylurea (DBU) formation after application of n-butylisocyanate and Benlate 50 DF and 50 SP fungicides to several soils at different water potentials and temperatures. Assessment of parent compounds, metabolites and carbon dioxide; Reduction in root and shoot growth rates; Effect of DBU on electron transport in isolated chloroplasts.

© New Phytologist (2004) doi: 10.1111/j.1469-8137.2004.01074.x [ABSTRACT FROM AUTHOR]