Solubility of Plant‐Food Elements as Modified by Fertilizers

This paper deals with the seasonal changes in the ~yater-soluble plant-food elements in a field of sugar ’beets at Rocky Ford, Colo., in 1912 , togeth, er with the effect of fertilizers on the amounts of the various elements reco.vered. The soil used was a sandy loam which had been cropped to alfalfa for a number of years. The alfalfa was crowned in the fall of 1911 and plowed in the spring of 1912 to a .depth of a.bout 8 inches. The roots were removed as co,mp.letely as possible and the ground planted to sugar beets in the first part of May. Eight plots were laid out and fertilizers applied in the spring of I912 at the following rates: Nothing; nitrate of soda, 3oo pounds at time of planting and 3o0 pounds when the beets were thinned; calcium cyanamid, 5oo pounds; superphosphate, 5oo pounds; bone meal, 5o0 poun’ds.; factory waste lime, 15 tons; composted manure, 14 tons; ordinary dry yard manure, 14 tons; yard manure, 14 tons plus 3oo pounds ammonium sulfate. The sugar goers were cared for in the usual manner and were irrigated uniformly, usually about every 12 days. The .composition of the yard manure and of the waste lime is given in Table I. The CO2, which was not determined in the lime, would bring the analysis up to practically IOO percent. Soil samples to a depth of I2 inches were taken every week from May 16 to Augus’t 12. The samples were analyzed biweekly for the water-soluble P20~, K20, SO~, and Mn20~. The fresh soils were extracted with distilled water in the proportion of one part of soil to five of water, .filtered through Pasteur-Chamberlain filters and analyzed according to the methods given in Bulletin No. 31, of the U. S. Būreau of Soils. In a’ddition to the above determinations, the nitrate nitrogen and the total nitrogen were determined each week. The results o.f the nitrogen measurements are given in another paper. 2