| Show I land Nutrients Removed d AlfalfaS Alfalfa S Needs Phosphorous for Fertilizer Alfalfa Is grown more widely In the stale slate of Utah than an anyone any anyone one other single Ingle irrigated crop As At a result considerable amount of ot fertilizer has bu and Is being used In the early days when land sand was virgin It ft contained adequate ad equate phosphorous or adequate e plant nutrients to grow mo most t crops that were being produced Some fifty to one hundred years later It was WI found that many of these land nutrients have been removed from the soil so that It Is now necessary to replace re replace re i place them in order to provide a satisfactory crop Alfalfa Needs With alfalfa the needs are primarily those of oC supplying phosphorous Alfalfa feeds heavily fly ily on phosphorous and needs It ItIn itIn itin In relatively large amounts In order to produce good yields According to Rex F F. F Nielson assistant professor of agronomy at Utah State has been found through a number of trials that the tho soils of Utah are I 1 wen well supplied with pota potassium another element el ment that alfalfa needs In relatively large amounts However However How How- ever he indicated It Is 19 available available avail avail- able In fairly large Targe quantities In Inmost Inmost inmost I most of at our Irrigation waters He went on to say that biotic relationship between nitrogen nl nl- trogen organisms on the plant root is capable of taking free nitrogen from Crom the air and fixing it so that additional ni nitrogen nitrogen nl- nl trogen need not be applied to al al- al fal falfa fa We have also run a number of tests In this area area he continued continued continued con con- and to date have never II had any evidence that nitrogen Is of any value to a a. crop of alf alfa atta This Is Jg rather fortunate then that we only need needs one commercial fertilizer to be used with alta alfafa tta fa We would suggest that barnyard or poultry manures manures manures man man- ures be used if they are available However they may be used more beneficially on other crops that I II I V will l also Use the he nitrogen that thatIs Is present 1 Rotation notation Rats He lie said that the problem r blem with alfalfa boles bois down t to primarily supplying the phosphorous fert Cert With Mth alfalfa which Is a n lived tong crop It la is better to utilize phosphate for forthe forthe forthe the fertilizer on a rotation basis that is If sugar beets which require require re re- quire a high amount of phosphorous phosphorous are arc grown fertilize the sugar beets to maintain or reach the phosphorous level that would be bo adequate for production production pro pro- of four or five years of alfalfa this to be followed with out any additional phosphorous phosphorous phosphorous on the alfalfa Nielson went on to say that If sugar beets are not grown then I It is desirable to apply phosphorous phosphorous 1 I I at the time the alfalfa Is 19 I i j being applied It can be applied broadcast prior t to planting or it may be applied after aster the crop cropIs cropIs cropis Is established About pounds of available 1 phosphorous applied every 2 to 4 years depending de- de depending depending de de- pending upon the nature of the soil and the productivity of the theland theland theland land Is usually adequate to take care rare of the needs of alfalfa This would mean Nielson added added added ad ad- ded If an application were made at nt the time of planting a subsequent subsequent sub sub- sequent app might be bo made 2 or 3 years later that would carry the alfalfa on through the normal 3 or 5 year rotation When Wilen to Apply A number of questions have I been asked regarding the time I of applying phosphorous to alfalfa alfalfa alfalfa alf alf- alfa It has been determined that It can be applied conveniently either In the spring or fall with little difference In effect Actually applications have been i made between first and second cutting on some very deficient sites and these there have proved tabe to ta tobe tobe be quite satisfactory There maybe may maybe maybe be some evidence to indicate that In areas where the winters are open and dry that fall application might be superior It also helps to distribute the work load ItIs It ItIs ItIs Is good to apply fertilizer inthe in inthe inthe the fall after peak work load is over and also in the spring when It doesn't interfere with other spring work J Nielson went on to say We Wo have noted in a number of fertilizers fertilizers fertilizers fert fert- trials that where a site is extreme y deficient even ona on ona I Ia a stand as old as 8 to 10 years that a surface application of phosphorous very often Increases the yield as much as per cent The residual effects of phosphorous on alfalfa last over several years We have run a number of trials where a a. single application of phosphorous on a highly deficient soil has increased yields as much as per cent five years after the initial cation Effects He added tEal tat this will n not hold on all situations and he lie emphasized that if the soil is really deficient a single apply atlon will last a long time The residual effects is usually proportional proportional proportional pro pro- to the amount of phosphorous applied as the larger applications will give a residual effect that will last longer than a a. smaller application atlon He continued We would suggest that before applying phosphorous to alfalfa the soil be collected and sent to the state soil soU testing laboratory at Logan where a good goad estimate may be made regarding the phosphorous status of the soils This is par par- particularly particularly valuable In determining those soils which are well sup- sup with phosphorous |
