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Show Mt, Pleasant Soil Authority Begins Series 0 Articles Commercial Fertilizers By MOKOXI A. SlAKt'llAS'V Soil SrlfiUlst Soil t'onsi-rvrttlon ST Ico Whsit kiiul una how imii'li com-meivuil com-meivuil fertilizer docs my farm need? rio:s- show !U figures and computations. lu ovor increasing numbers North Sanpete fanners ami agricultural agri-cultural people are asking this question. Jhe latest available data tor Sanpete County reveals that for general farm crops two major elements are present in only limited amounts or. in many cases are very low. These two elements are nitrogen and phosphorus. Only one of these, phosphorus, is a strictly commercial fertilizer. The nitrogent question will he discussed later in connection with J barnyard and green manures. ' j For the purpose of this discus- , sion we will consider only the m- , organic element of phosphorus. We must look to commercial sources outside the farm for supplies of this very vital portion ot plant food. Manures and composts produced pro-duced on the farm from residues of farm crops grown on soils low-in low-in phosphorus must of necessity be low in this element. A normal soil should have about 16 parts per million tPPMl of available phosphorus. Analectical data for Sanpete County soils shows a variation of from 5 PPM to 9 PPM (parts per million). This variation is due to the type of soil, length of cropping history and amounts of crops produced over that period. Soils that have never been cropped or irrigated are always a few points higher in phosphorus than the same soils under cultivation for a number of years. trt nr,tc that It IS Ol IlliricaL soils with less than 1 PPM are not rare, but are rather common in Sanpete County. There are approximately 4 million mil-lion pounds of soil on a surface acre of soil one foot in depth. As plants do most of their feeding in nv the first 12 inches of soil we may ' use this figure as a basis for cal- i culating the phosphorus need. Four million pounds of soil con- taining 16 parts per million avail- T able phosphorus would be 4x16 or J 64 pounds of available phosphorus i necessary for .normal plant A growth. Thus if the soil tested 5 PPM it would be necessary to .j add 60 pounds available phos- -j phorus. which would be 300 pounds of 20 per cent or 150 of 43 per 1 cent fertilizer. In addition laboratory results i show that when commercial phos- J phates are added to a soil high in f calcium carbonate (lime), that the calcium will "grab up" or as is j commonly termed, revert the phosphate to a form that is not- usable by the plants. J Making allowances for this (factor and adding a conservative 25 per cent more phosphate would i bring the requirements of the soil in Sanpete to about 80 pounds - of available phosphorus. This j would be 400 pounds per acre of I 20 per cent phosphate fertilizer or 1 200 pounds of the 43 per cent. I Phosphorus is a relatively stable element in the soil, as it cannot be Boning Up 1 S?f While his father vacations before be-fore assuming presidency of Columbia University, Capt John Eisenhower studies there. He's shown leaving . Low Memorial Library after registering for an English refresher course. Later he will-teach at West Point. removed except through cropping or erosion. In direct contrast to nitrogen, it is not very soluable in water and will not be leached out through excessive irrigation. The best way to apply phosphate to the land is by using some machine which places it, not on top iof but in the soil, where the plant roots may rcah it. Fertilizer attachments to drills, corn planters, beet planters, etc., are ideal for this purpose, he next best method is to apply it with manure where they both can be worked into the topsoil. the least desirable and most common is by broadcasting over the surface of the land. The time of application in relation to the seasons does not seem to make much difference. In general, most legumes and especially the clovers are most responsive to phosphate fertilizers, while small grains and grasses are the least responsible and give poorest results. Sugar beets require both phosphate phos-phate and organic fertilizer for best results. Thus one should use it on beets or legumes at the start of the rotation, in preference to applying it to small grains or grasses. It is very effective on grass and clover mixtures where healthy clover plants may use it and in turn furnish more nitrogen to the I soil for later use by other plants. |