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Show U S V Cl'TEf-i NEKI) OF HOOT) FEliTI LIZER ' FOT7 TO T?nOitTCTTOT OF A1TJ All'aH'a is ,ui-ovn more widely in the state of Utah than any one oilier single irrigated crop. As a result, : nsidevalil- nmoiu.l of fertilizer lias and is hom; used. In (he early days wlu-.i land was virgin, it contained adeci;;a i ; y.hu si;l!oi-)ns er a'le;';a.le plmit nutrients to -row most crops that were heinu- pro- duced. Some fifty to a hundred years later, it was found that many of these land nutrients have been removed from the soil so that it is now necessary to replace them in order to the spring when it doesn't interfere in-terfere with other spring work. Nielson went on to say, "We have noted in a number of f.itilizcr trials that where a site is extremely deficient, even on a stand as old as 8 to 10 years, that a surface application applica-tion of phosphorous very often will increase the yield as much as lCOr;. The residual effects of phosphorous on alfalfa last over several years. We have run a number of trials where a single application of phosphorous phos-phorous on a highly deficient soil has increased the yields as much as 100 five years after the initial application." He added that this will not hold on all situations, and he emphasized that if the soil is really deficient, a single application ap-plication will last a long time. "The residual effect is usually proportional to the amount of phosphorous applied, as the larger applications will give a residual effect that will last longer than a smaller application." appli-cation." He continued, "We would suggest that before applying ap-plying phosphorous to alfalfa, that soil be collected and sent to the state soil testing laboratory labor-atory at Logan where a good estimate may be made regarding regard-ing the phosphorous status of the soils. This is particularly valuable in determining those soils which are well supplied with phosphorous." 4 will also use the nitrogen that is present." He said that the problem with ahali'a boils down primarily pri-marily to supplying the phosphorous phos-phorous fertilizer. With alfalfa, which is a lon-lived perennial crop, it is better to utilize phosphate phos-phate for the fertilizer on a rotation basis, that is, if sugar toets, which require a high amount of phosphorous, are grown, fertilize the sugar beets to maintain or reach the phosphorous phos-phorous level that would be adequate for production of four or five years of alfalfa, this to be followed without any additional ad-ditional phosphorous on the alfalfa Nielson went on to say that if sugar beets are not grown, then it is desirable to apply phosphorous at the time the alTalfa is being planted. It can be applied broadcast prior to planting, or it may be applied after the crop is established. About 100 pounds of available P205, phosphorous, applied every two to four years, depending de-pending upon the nature of the soil and the productivity of the land, is usually adequate to take care cf the needs of alfalfa. alf-alfa. "This would mean," Nielson Niel-son added, "if an application were made at the time of planting, a subsequent application appli-cation might be made 2 or 3 years later that would carry the alfalfa on through the normal nor-mal 3 to 5 year rotation." A number of questions have been asked regarding the time of applying phosphorous to alfalfa. alf-alfa. It has been determined that it can be applied conveniently con-veniently either in the spring or fall with little difference in effect. Actually, applications have been made between the firct and second cutting on some very deficient sites and these have proved to be quite satisfactory- There may be some evidence to indicate that in areas where the winters are open and dry, that fall application ap-plication might be superior. It also helps to distribute the work load. It' is good to apply fertilizer in the fall after peak work load is over and also in produce a satisfactory crop With alfalfa, the needs are primarily those of supplying phosphorous. AlfaKa feeds heavily hea-vily on phosphorous and needs it in relatively large amounts in order to produce good yields. According to Rex F. Nielson assistant professor of agronomy at Utah State University, it has been found through a number of trials that the soils of Utah are well supplied with potassium, potas-sium, another element that alfalfa alf-alfa needs in relatively large amounts. "However." he indicated, indi-cated, "it is available in fairly large quantities in most of our irrigation waters." He went on to say that a Symbiotic relationship between nitrogen-fixing organisms on the plant root is capable of taking free nitrogen from the air and fixing it so that additional ad-ditional nitrogen need not be applied to alfalfa. "We have also run a number num-ber of tests in this area," he continuea, "and to date have never had any evidence that nitrogen is of any value to a crop of alfalfa. This is rather fortunate then, that we need only one commercial fertilizer to be used with alfalfa. We would suggest that barnyard or poultry manures be used if they are available. However, they may be used more beneficially bene-ficially on other crops that |