Saturation degree of soil and nutrient delivery to the crop

The data all emphasize the fact that more nutrients were delivered by the crops because of the higher degree of the soil saturation even of only a limited part of the soil, This area of soil was seemingly large enough to prohibit injury through excessive salt concentrations. These increased movements of the nutrients into the crops were roughly paralleled by increases in forage yields, though not directly so. Thus, there has resulted in most cases increased concentration of nutrients within the crops to give them higher forage feed value. Thus, the efficiency of the treated soils in terms of tonnage yield per unit of nutrient delivered is lower than the efficiency of the untreated soils, but it may be far more efficient in producing an animal feed of higher calcium, phosphorus, and protein concentrations. The increased use of nitrogen by the crop points to the significance of calcium and phosphorus in making this phase of plant metabolism operate effectively in case of the nonlegumes as well as for legumes. Since calcium and phosphorus are the two most significant soil needs in the corn belt, as shown by past agronomic experience, by soil development, and by crops in their ecological array, we may well look forward to their wider use. For more effectiveness in practice, however, limestone and phosphate should be applied in more limited soil areas rather than distributed through the soil zone. Possibly not only the concentration within limited soil zones should deserve consideration, but also some efforts toward retardation of their rate of adsorption for reaction with the soil. Effectiveness of granular forms of such soil treatments may be premised on the greater efficiency of the nutrients when in areas of higher degrees of saturation. Efforts to improve applications for such effectiveness should give results in terms of crop increases. Since the very acid clay is active even to the point of removing calcium from the mineral lattice and since a calcium clay is not so active in the removal of bases from plant roots, perhaps the higher degree of calcium saturation in limited soil areas lessens the activity by the soil in adsorbing the anion phosphorus. If this is the case, then the applied phosphorus remains longer in the soil without reacting with it and may explain, in part, the greater efficiency of phosphates when used on limed soils or those liberally stocked with calcium. These results suggest most forcefully that in liming and fertilizing the soil, attention must go to the degree of saturation of the soil. The use of such soil treatments will be more effective when applied in limited soil areas to feed the plant than when applied through greater areas to modify the soil condition.