| Show 5 rr t e 41 i Alfalfa A falfa Utah's Biggest Crop Needs Plenty of Phosphorous Alfalfa la Js grown more widely In Inthe Inthe inthe the state of Utah than any anyone one other single Irrigated crop As A ft a result considerable amount of or fertilizer fer fer- has haa and Is Js being used In Inho Inho ho he early days when land was VIrgin Virgin virgin vir Vir- gin It contained adequate phosphorous phosphorous or adequate plant nutrients nutrients to grow most crops that were being produced Some Bome fifty to one onehundred onehundred hundred years later It was found that many of Clr these land nutrients have been removed from the soil so that It is now necessary to re replace reo place them in order to produce a k satisfactory cr crop p. p Alfalfa Needs With alfalfa the needs are primarily primarily pd- pd marily those of or supplying Alfalfa feeds heavily on phosphorous and needs it In relatively relatively rela rela- Jarge large amounts In order to I produce good yields According to i I Rex F F. Nielson assistant professor protes- protes sor of or agronomy at Pot Utah State University It has been found through a number of or trials that he soils of Utah are well wen sup sup- pled with potassium another clement cle- cle ment meat ment that alfalfa needs in relatively relatively rela rela- large amounts However too he Indicated it is available In fairly large qu quantities in most of ot otur our ur irrigation on waters He SIe went on to say that a symbiotic sym sym- biotic relationship nitro nitro- fixing on-fixing organisms on the plant root Is capable of taking free tree nitrogen nitrogen nitro nitro- gen en from the air and fixing It co so coh 0 hat h t additional nitrogen need not b bo J applied to alfalfa We have also run a number nf of tests In this this arcs nrc he continued and to date date have never had any evidence ev that nitrogen is 13 of or any value to a crop of alfalfa This s rather father r fortunate then that we only need one commercial fertilizer fertiliser er to be used with alfalfa We would suggest that barnyard f Jr poultry manures be used If they are ArD available However they nay bJ used more beneficially on other crops that will also use the nitrogen nitrogen nitrogen nitro nitro- gen that Is present Utilize Phosphorus He lie said that the problem with alfalfa bolls down to primarily applying supplying the phosphorous fertilizer pr er r. r With alfalfa which is a long long- Jived perennial crop It Is better betterto to oW to utilize phosphate for the fertilizer fertilizer fertl lizer on a 1 rotation basis that Is If sugar beets which require a high amount amoun t of phosphorous are grown fertilize the sugar beets to maintain or rea reach h the phosphorous phosphor phosphor- ous level that would be adequate for production of four or live five years tot of alfalfa this to be followed without without with with- out tOUt any additional phosphorous on alfalfa Nielson went on to say that if Sf sugar ugar beets are not grown then ItLa it itIs li La desirable to apply phosphorous At the time the alfalfa is Js being planted planted- It can be be applied broad broadcast broadcast broadcast cast prior to planting or it may maybe maybe maybe be applied after the crop is About pounds of available available avail avail- able phosphorous applied every 2 to 4 years depending upon the nature of the soil and the productivity productivity pro pro- of the land Is 13 usually adequate to take care of the needs ct of alfalfa This would mean NIelson lelson Nielson added if an application were made at the time of planting ft a subsequent application might be made 2 or 3 years later that would carry arry the alfalfa on through the normal 3 to 5 year rotation Questions Question Solved A number of questions have been asked regarding the tho time timo of c applying phosphorous to alfalfa It has bat been determined that it can be applied conveniently either in 14 inthe the tho spring or fall with little dif dif- o f rence in effect Actually appu appU Caton hv hays been m ad 4 between first and second cutting on some DOme very deficient sites and these have proved to be quite satisfactory There may be some evidence to Indicate in indicate indicate In- In that in areas where the winters are open and dry that fall faU application 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 the spring when it doesn't Interfere with other spring work Nielson went on to say We have not noted in a number of fertilizer fertilizer fer ter- trials that where a site is extremely deficient even on a n stand as old od as 8 to 10 years that thata a surface application of or phosphorous phosphor ous very often will IU Increase the yield as much as per cent The residual effects of phosphorous on alfalfa last over several years We have run a It number of trials where a sl single gle application of phosphor I I ous on a highly deficient soil has increased yields as much as per cent five years after Her the initial initial ini ini- I tl l application Residual Effect He Ile added that this will not hold holdon on all situations and he ne emphasized emphasized emphasized sized that if the soil is really deficient deficient de de- a single application will last a long time The residual ef effect effect ef- ef is usually proportional to the amount of phosphorous applied as the larger applications will give a residual effect that will last long long- ir than a smaller application He continued suggest that before applying phosphorous to alfalfa that s soil soil-be ll be collected and sent to the state soil soU testing laboratory laboratory laboratory lab lab- oratory at Logan where a good estimate may maybe be made regarding the phosphorous status of the soils This is particularly valuable In determining those soils which are well supplied d with r. r ous |
