The double‐buffer (DB) feature of the recently‐published Yuan method was applied to the Shoemaker‐McLean‐Pratt (SMP) method at several buffer pH levels, shaking times, and soil/solution ratios. The results, based on regression analysis of buffer‐indicated vs. Ca(OH)2‐titrated acidities, indicate that the widely used SMP single‐buffer (SB) method can be improved considerably by incorporation of DB, quick‐test, and mathematical‐adjustment features. However, the SMP‐SB method is still probably the most satisfactory compromise between simplicity of measurement and reasonable accuracy of results for soils of a wide range in lime requirement (LR). The SMP‐DB method with narrow soil/solution ratio and shorter shaking time gave excellent indication of soil LR when adjusted for incomplete reaction with the soil during the shorter “quick‐test” reaction time. This adaptation which looks very promising as an improved method (especially for use on soils of low LR where the SMP‐SB method is known to lack desired accuracy) is included as a recommended improvement of the SMP‐SB method.

Three soils (Toledo silty clay, Rossmoyne silt loam, and Wauseon sandy loam) in greenhouse microplots were treated with chemical, chemical + straw, and manure sources of N, P, and K, cropped or left bare, and subjected to simulated rainfall. Phosphorus moving in runoff sediments, runoff solution, and leachate was measured. Most P moved as a component of sediments. Cropping decreased sediment and solution losses while manure generally increased losses in both. Most P moving in runoff solution was inorganic. However, except where percolation swept inorganic P downward without reaction with the soil, most P moving in leachate was organic. Fractionations of soil P revealed that P treatments increased the HN4Cl‐ and NH4F‐extractable fractions markedly, had less effect on the NaOH‐extractable fraction, and had still less effect on the H2SO4‐extractable and organic fractions. All phosphorus sources markedly increased the equilibrium P concentrations (EPC) of all soils. Manure increased EPC more than the other sources in the Rossmoyne and Wauseon soils. The tendency for more sediment P to be lost from manure and for manure‐treated soil to mobilize P into solution makes erosion control especially important, if much manure is to be applied to soils, and if eutrophication of surface waters is to be minimized.

Nitrogen, P, and K as manure, chemical fertilizers + straw, or chemical fertilizers alone were added to microplots of soils, which were then either cropped to wheat (Triticum aestivum) or left bare, and finally subjected to simulated rainfall. The N, P, and K were each applied at 224 kg/ha in the forms of: (i) N‐ and P‐enriched cow manure (7.35 metric tons/ha, dry weight); (ii) urea, triplesuperphosphate (TSP), and KCI + straw at the same weight of dry matter as the manure; and (iii) fertilizers alone. A 5‐day rainfall sequence was imposed with varying intensities, durations, and soil slopes. The movement of N generally increased as the quantities of solids, runoff, and leachate increased. Where discrepancies occurred, they could usually be explained by differences in structure, crusting of the soils, or clogging of their pores by manure, or by effects of straw on soil permeability to water or on increased microbial activity. In general, almost all the mineral N moving in the leachate, and about half of that moving in runoff, was in NO3− form