Show PRACTICE G GOOD OD FOR POTATOES Bt 8 Geo Stewart I In n Charge of FI Fie old Crops Experiment Station U Utah ah Agricultural College practices vary nary consid ably In the tho East commercial terU are in general use especially In the Ule truc trucking sections Phosphorus potash and nitrogen are frequently applied This form of ot hae has not yet become general In the tho West Potato to growers of or Utah and nod adjacent states depend on farm manure and sod-matter sod and for tor the tb-e fertilizing elements Occasionally late fall 0 or of arly spring growth of ot alfalfa aUala la is turned under but tho the usual practice Is to make hay of this and return to the land the manure mode made by the tha animals to o which the tho shay hay is 18 fed With so ea many cattle on the summer I I ranges this is probably the most most profItable prof- prof s system stem of fertilizing the tho land The functions of or organic matter of ot farm manure and sod Is 18 principally to ati ply organic matter In the end 0 decomposition Results and the fertilizing elements are aro added to the soil soU in a a. a readily available form Important however as the fertilizing elements may bo the tho Indirect effect Is still sUll more Important Coarse man manure mans mansure ure and large roots root are hindrances to cultivation and but under favorable Ct conditions conditions' these are educed to fine line particles which are still undergoing active o decay and which mix readily with the s 9 soil ll 1 particles par par- Organic matter In such Buch condition con can is valuable in two distinct wn ways s 's 1 b by Increasing the water- water holding capacity and 2 by creating a n condition of medium porosity In the soil 1011 Increases water water holding capacity Decaying or organic matter absorbs water ater much as itS does a sponge Because Because Because Be Be- cause many of the particles are hollow hollow hollow hol hol- low the surface to which films of water can enn cling Is much greater than on solid soUd soil particles of the same volume In addition organic matter 0 d mains j a substance called humic acid neld w wh hag lids has the power of hol holdIng hold hold- lug lag many times time its own weight of water In a loo loose e chemical tion Lion Controls porosity and aeration r- r Besides matter loosens clay soils and rend renders rs them porous It has the opposite effect on coarse sands and extremely pOr porus s s soils us in 10 which It serves as assort sort of binder as aswell aswell aswell well as a n retainer of or water It Is common knowledge that wet sand even Jt Sf n nearly arly pure and very coarse will hold together with greater great great- er tenacity than the tho same sand when deprived of or Its tJ Organic Ie j matter therefore consolidates loose soils both hoth by hy supplying a binding agent and by a retainer of ot water A high degree of looseness In clays days and a high degree of consolidation consolidation consoli consoli- dation in sands increase the water- water holding holding powers of such soils These I conditions also encourage more de der deI desirable I aeration and uniformity of i Compact Comp ct clays have too little pore space to hold much water to permit the easy exchange of ot gasses between the soil solI and the atmosphere Hoots and bacteria both need Heed air all o oxygen also helps in rendering mineral plant foods soluble S Sandy soils are lU likely el to ne no too hot and clayey soils too cold Flit Th extra moisture and the consolidation I in sandy soils solis moderate the temperature tempera tempera- 1 ture turo of these soils and thereby de der decreases I creases creases evaporation in heavy soils SOliS the Increase of ot pore space encourages es esmore more through ventilation As the water wa wa- water ter content Increases to about med medd medium medium ium turn the the pore space increases If It more water Is added the volume de decreases do- do creases and consequently the air Apace It Is at this point of ot greatest volume that soils aerate most readily and consequently warm up most rap- rap Idly Roots can penetrate more easily and more deeply because air all is available available avail avail- able at greater depths and because there thore is loss less resistance In all respects re 10 ro- ro the soil Is Is' Is then in the most favorable fa condition for tor plant growth u On this account this condition In soil u II 1 rd Is known as the optimum Lot n w nv o meaning the best water content Actively Actively Ac Ac- decaying organic matter mattor tends to bring all soils to this desirable condition |