RESULT OF SUBSOIL IRRIGATION RESEARCH OF ALFALFA GROWN FOR GREEN FEED IN VOLGO-AKHTUBINSKAYA FLOOD PLANT

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1 Journl of Agriculturl Sciences Vol. 53, No 2, 2008 UDC: Originl scientific pper RESULT OF SUBSOIL IRRIGATION RESEARCH OF ALFALFA GROWN FOR GREEN FEED IN VOLGO-AKHTUBINSKAYA FLOOD PLANT A. Akhmedov 1 Astrct: Relevnce of susoil irrigtion usge for growing feed crops on lluvil medow soils is shown. Distriution of pjezometric pressure, long the wter emitter line during the irrigting period, is nlyzed. Formtion of moisture ptterns in the soil regrding the quntities of irrigting wter nd emitters design re considered. In order to define the chrcteristics of moisture ptterns in the soil, depending on the quntities of irrigting wter, the rtios of verticl wter spreding K v nd forms K f re clculted. Expediency of usge low irrigting rtes is sustntited. As result of reserch, mthemticl reltions were derived in order to define wter outlys in the emitters mde of pottery tues with dimeter 50 mm under wter pressure t the line m. It is determined tht usge of susoil irrigtion llows increse of commercil crop hrvest, significntly sve wter resources, lour nd energy compring to sprinkling. Introduction For increse of irrigted lnd efficiency, the choice of ecologiclly sfe technology nd technologicl mens for wtering in view of irrigtion wter economy hs got the gret importnce during the lst yers. The leding countries of the world prefer such wys of wtering which llow djustment of wter-sumission ccording to wter consumption of griculturl crops. In prctice ll locl irrigtion methods meet these requirements including susoil irrigtion (SSI). Using of the given irrigtion method llows to crete optimum wter-ir regime 1 Askr Ahmedov, PhD, ssistnt professor t the chir of Technologies in mngement of nturl resources t Ecology Lnd Reclmtion Deprtment of Volgogrd Stte Agriculture Acdemy Universitetsky prospect, 26. Volgogrd, Russi. Tel. (8442)

2 114 A. Akhmedov of soil, to keep its structure nd to improve ertion, to provide optimum for plnts cpillry humidifiction of soil. As result the crop cpcity of griculturl crops increses in % in comprison with sprinkler irrigtion. However opportunities of the susoil irrigtion re not completely relized ecuse of the insufficient studying level of wtering theoreticl ses nd technologies. In this connection there ws necessity of crrying out the reserch lines, directed on the development of the lflf susoil irrigtion technology for the green forge in Volg-Akhtuinsky flood plnt. By virtue of geogrphicl conditions the flood plnt climte is shrply continentl nd droughty. The mid-nnul temperture of ir is out 8 C. The volume of precipittion is mm. During the wrm period (from April till Octoer) it flls out 2/3 of precipittion. On the verge, the evportion is estimted to mm. In the geo-morphologicl reltion, the plot is in the su-zone of lluvil medow complex lightly lomy soils. The content of the humus is low. The verge is 0,86-0,88 % of the dry soil in the 0-0,5 m lyer. On the plot with the sprinkler irrigtion, the density hs mde 1,44 t/m, nd t the SSI - 1,50 t/m for meter ground lyer. The lest moisture cpcity is ccordingly 19,31% nd 19,27 % of the dry soil weight. The soils re not sline. Methods Studying of SSI systems nd regime of lflf irrigtion on the green feed in comprison with sprinkler irrigtion were crried out y B.A. D o s p e h o v 's (1979), G.V. Vedenjpin (1973), V.N. P e r egudov (1970). In view of the soil mechnicl structure nd filtrtion properties for mintennce of the optimum of humidifiction regime re stipulted y miniml pipes instlltion depth of the susoil irrigtion -0,5 m nd mesures on prevention of irrigtion wter lekge in the lower lyers of the soil structure. With this end of view under the humidifictor, it is rrnged the un-filtrtion polyethylene screen in width 0,25-0,30 m. The screen ove the humidifictor is rrnged for the prevention of the ooze mud nd increse in distnce etween humidifictors t the expense of the increse in contour of humidifiction. On the experimentl plot of the susoil irrigtion in the conditions pproched to industril, two constructions of humidifictors produced from potter's pipes with internl dimeter of 50 mm nd length of 333 mm hve een investigted. In the first construction the pipes re connected with the polyethylene clutches of the 0,1 m width, distnce etween humidifictors is 2,0.In the second construction the pipes re lid closely to ech other, their joints re not isolted, distnce etween humidifictors is 1,5 nd 2,0 m. All humidifictors re produced with the length of 125 m. A is of the humidifictors is 0,002. Detiled nd deep studying of the rising questions were crried out y following supervision nd ccounts: density of ground - with the method of cutting

3 Alflf susoil irrigtion 115 rings (under K chinskiy); density of the hrd phses of the soil - with the picnometricl method; humidity - with the weight method; the porosity nd the full moisture cpcity- with the clcultion method; the lest moisture cpcity with the flooding method. The ccount of productivity ws determined with the method of registrtion pltforms (4-5 m 2 ), in qudruple frequency. Mthemticl dt processing ws crried out with the help of correltion nd dispersive nlyses on the computer, with the help of pplied progrms on mthemticl sttistics. Dynmics of humidity in the field conditions ws studied on the specil wter-lnce pltforms locted t digonl of the llotment on distnce of 20 m from the hed, in the middle nd 20 m t the end of the humidifictor. Humidity tests in cross-section etween the humidifictors were tken ove the humidifictor through every 0,2 m nd in the middle etween the humidifictors y vrints. Humidity tests on verticl were selected through 0,1 m on depth up to 1 m in qudruple frequency up to, nd fter the wtering, in dy or two. The vlue of the irrigtion norm ws clculted under the formul of cdemicin A.N.K ostjkov (1960) in view of the fctor which is tking into ccount the chrcter of distriution of wter in ground: m = H 100 (β h β h )γ o, where - m is the irrigtion norm, m/h; - the fctor, which is tking into ccount the wter distriution chrcter in the soil, coming from the humidifictors, chnges in limits from 0,4 up to 0,7 depending on the mechnicl structure of the soil nd on the distnce etween the humidifictors; H - cpcity of the clcultion soil lyer (H = 0,8 m); β h - humidity of the clcultion soil lyer, HB ; β h the soil humidity on the plot efore the wtering, % ; γ o the soil density, t/m 3. Results Efficiency of the susoil irrigtion systems is in direct dependence on the correct estlishment of the wtering technicl prmeters, on the distnces etween the susoil humidifictors nd the depth of their lying, optimiztion of the irrigtion norms, of the wter sorption speed, of the length of the susoil humidifictors. The nlysis of the reserches of vrious uthors nd lso our own reserches hs llowed to drw conclusion, tht in ll cses the distnce etween humidifictors for the continuous sowing cultures should e ppointed from the close contours conditions of the humidifiction nd to coordinte with the soil cpillry properties. The quntity of the evporting wter t the susoil irrigtion is minimlly, ut the filtrtion losses, especil in homogeneous soils, cn e significnt. Besides the humidifictors construction, their size is in direct dependence on the

4 116 A. Akhmedov size of the piezometricl pressure ove n xis of the humidifictor nd the regime of the soil humidity. By the studying of the piezometricl pressure on the humidifictors length, the seven piezometers hve een estlished in the following order. The first is in 2,5 m from the hed of the humidifictor, the lst is on the sme distnce from the end-prt of the humidifictor. The sic prts were lid through every 20 m from the hed of the humidifictor. The size of the piezometricl pressures ws mesured from the humidifictor xis, including piezometer in the pressure hed tnk, the counting out the piezometers undertook every 10 minutes, nd then - 30 minutes, up to the constnt vlue. By the nlysis of the verge humidity dynmics in the soil it is necessry to note non-uniformity of its distriution on the length of the humidifictor. At the lmost identicl pre-irrigtion soil humidity in the lyer 0-0,8 m on the humidifictor length, the soil humidity, fter the wtering termintion, decreses up to 5-th section nd then increses up to the end- prt. At distnce of 0,25 m from the humidifictor xis in the 5-th section this vlue in comprison with the 1st section decreses on 8,7 %, ut t the humidifictor end on 1,9 %. During the time the moisture redistriution is oserved in peripherl horizons of the humidifictors. The distriution chrcter remins unchnged: the gretest vlues of the soil humidity re in the hed nd in the end-prt of the humidifictor, the lest re in the middle prt. During the 1,3,5,7 dys fter the wtering the humidity continues to decrese, reching the lmost pre-irrigtion vlues t the lst supervision. As it is known, in this cse the moisture possesses the gretest moility. Regulr mesurements hve shown, tht the sic mount of irrigtion wter is ccumulted in the soil lyer of 0 0,8 m nd 22,5 % gets in the rle horizon, 72 % in the lyer of 0,3-0,6 m, nd only 5,5% is infiltrted. The further supervision for the soil humidity fter the wtering shows tht the chrcter of moisture distriution in the soil horizons on the length of humidifictor is miguous during the time fter the wtering termintion. Compring with grphic dependences of the verge dynmics of soil humidity on the length of the humidifictor, it is necessry to note concurrences of the form of curves for the sme chinks sections. The difference in the solute mrks of humidity, depending on the rrngement of the chinks sections on the humidifictor length, coincides on chrcter with the dynmics of the piezometricl pressure. The qulity of the soil humidifiction in mny respects depends on the wter distriution uniformity t ll tuulr humidifictors. Non-oservnce of this condition y designing of the susoil irrigtion systems cuses the fluctutions of the piezometricl pressures long the length of the humidifictor. Hence, the irregulrity of the soil humidifiction long the length of the humidifictor cuses instility of the griculturl crops. Studying of the contour formtion questions depending on the humidifictor design, on the wy of the irrigtion wter sumission into the ground, on the irrigtion norm nd the pressure ws crried out in the lortory - irrigtion instl-

5 Alflf susoil irrigtion 117 ltion. It operted y following: wter-pressure hed tnk - pressure regultor - reserched humidifictor. The processing of the cmerl mterils y field reserches ws undertken with the help of usul receptions of mthemticl sttistics. The size of reserched pressures did not exceed 0,2-0,7 m. Let's consider results of experiences. In the 1st type of the construction the form of the moistened humidifiction contour comes nerer to rectngulr or round, little extending in the lower prt of the contour, lying under the humidifictor tht is cused y the entering of moisture first upwrds nd in the sides, then downwrds. The sizes nd the res of the humidifiction contours re given in the scheme 1 depending on the design fetures of the humidifictors nd the vlue of the pressure. From the scheme it is cler, tht on the verge re of the moistened contour in the 2nd type of the humidifictor design is t 0,04-0,08 m or more, thn in 1st. The oservtion T. 1. The humidity contour dimensions ( fter wtering, in 18 hours) H, m The humidity D B, m D r, m S, m 2 0,60 0,60 0,30 0,30 0,20 0,20 0,60 0,60 0,30 0,30 0,20 0,20 The type of the humidifictor I 0,47 0,41 0,34 0,41 0,38 0,45 The type of the humidifictor II 0,47 0,42 0,35 0,43 0,39 0,45 1,31 1,44 1,00 1,39 0,94 1,11 0,91 1,03 1,37 1,48 1,05 1,33 0,97 1,16 0,94 1,08 1,59 2,01 1,25 2,38 1,06 2,15 0,79 1,27 1,63 2,09 1,29 2,41 1,12 2,19 0,84 1,33 In the 2nd type of construction, the form of the moistened contour comes nerer to n ellipse tht is cused y the entering of moisture first in the sides nd then upwrds nd downwrds.

6 118 A. Akhmedov At the pressure incresed from 0,7 m nd more, the re of humidifiction increses insignificntly, nerly 0,05-0,07 m in the horizontl direction, ut here is dnger of the soil suffusion nd the wter outgoing on soil surfce. Hence, it is expedient to pply the un-filtrtion screen. Screens llow to increse distnce etween the humidifictors nd to come up to 1,4-1,5 m, nd esides tht the ppliction of screen llows incresing of the re of the moistened contour in 1,3-1,7 times. Thus the optiml is pressure of 0,5-0,6 m. For the studying of the irrigtion norm influence on the contours formtion of the humidifiction the wtering norms of 600 nd 350 m 3 /h re considered. For the definition of the humidifiction contours chrcteristic depending on the irrigtion norms were counted up y ll fctors of verticl distriution nd forms of f. Fctor estimtes the optimlity of the humidifiction contour, i.e. this vlues ttitude of the contour humidifiction distriution upwrds ( 1 ) nd downwrds ( 2 ) from the xis of the humidifictor, nd f - the ttitude of the height of the humidifiction contour D B to width D r. Hence, t the increse of K the irrigting wter losses for the filtrtion re decresed nd reduction of the vlue K f llows to increse distnces etween the humidifictors. The vlues of the fctors nd K f re clculted y us nd re given in the scheme 2. Time fter wtering T. 2. The influence of wtering norms vlue on the humidifiction contour distriution Humidifiction contour prmeters 1,m 2,m D B,m D g,m K K f Wtering norm 600 m 3 /h 0 0,29 0,48 0,77 1,16 0,60 0,66 1 0,28 0,64 0,92 1,27 0,44 0,72 3 0,19 0,67 0,86 1,06 0,28 0,71 5 0,09 0,36 0,45 0,60 0,25 0,75 7 0,03 0,13 0,16 0,29 0,23 0,55 Wtering norm 350 m 3 /h 0 0,25 0,40 0,65 1,05 0,62 0,61 1 0,24 0,53 0,77 1,10 0,45 0,70 3 0,27 0,58 0,75 0,94 0,25 0,79 5 0,08 0,32 0,40 0,56 0,25 0,71 7 0,03 0,11 0,14 0,26 0,27 0,54

7 Alflf susoil irrigtion 119 Studying of wter expense depending on the susoil humidifictor ws crried out on the experimentl - field instlltion. The potter s pipes humidifictors were tested t the wter pressures in the hed from 0,10 up to 0,70 m. During experience the constnt wter pressure in the hed of the humidifictor ws supported. The control ws crried out with the help of piezometers. The wter expense vlue ws fixed through every 10 minutes from the eginning of supervision. Tests were crried out t the pre-irrigtion humidity of soil %HB. With increse of pressures the wter expense in the hed of the lst ws incresed. So, t the pressure of 0,1 m the wter expense fter 10 minutes of work ws 0,30 l/s, t the pressure of 0,30 m - 0,51, 0,5 m - 0,645 nd 0,7 m - 0,790 l/s, i.e. t the increse of the pressure to 0,6 m the expense hs incresed in 2,63 times. The instlled vlue of wter expense in the humidifictor hed ws: for the pressure of 0,7 m - 0,235 l/s, for 0, 5 m - 0,160, for 0,3 m-0,125, for 0,1 m - 0,040 /s. Experimentl dependences q = f (t) were pproximted with the help of the eqution q = ( + t) c + d, where q is the wter expense in the humidifictor,l/s; t - time from the eginning of wtering, minutes; c- power index equl-1;,, d - fctors, which numericl vlues re experimentl determined. For our conditions curves q = f (t) re descried y the following equtions: q = 6,55 T-1 + 0,22 t the pressure of 0,7 m; q = 5,89 T-1 + 0,15 t the pressure of 0,5 m; q = 4,65 T-1 + 0,11 t the pressure of 0,3 m; q = 3,21 T-1 + 0,04 t the pressure of 0,1 m. At the reduction of the pressure the wter expense in the humidifictor hed decreses. At t there comes full stiliztion of wter expense, nd t t 0, ccording the equtions, q, ut does not exceed limiting sorption ility of the pipe. The nlysis of the received dt shows (fig. 1), tht in ll cses the points in the chosen scle re lid pproximtely on the direct line type y= x+. Empiricl formuls re selected with the help of the leveled points method. The received dependences with sufficient ccurcy re proved y the checking of some points on strightforwrdness t ech vrint. The more is sorption ility of the pipe - humidifictor t identicl ises, the higher the stright line is lid.

8 120 A. Akhmedov Time fter the eginning hving wtered, min The wter expense, l/s 0,4 0,35 0,3 0,25 0,2 0,15 0,1 0, ,1 0,2 0,3 0,4 0,5 0,6 0,7 0, Pressure in hed of dmpener, m Fig. 1. Dependence of the wter expense in dmpeners from pressure during hving wtered Generl received eqution nd considering, tht dependence of the given humidifictor expense on time hs hyperolic chrcter; we shll conclude the common eqution connecting the specific time from the wtering eginning nd the pressure in the hed of the dmpener: Q = 0,0031+4,5080-0,967 The men-qudrtic clculting expense of devition from ctul t the considered pressures during ll wtering chnges within the limits of 0,36-4,18 %. The scope of the received dependences is limited t pressure (H= 0,1-0,7 m) nd on the time (T = minutes) to ppernce of the estlished expenses. Using clculting dependences it is possile to count up supply of irrigted wter for ny time intervl nd t vrious pressures, to do interpoltion, extrpoltion nd to define the clculting expenses of wter in the humidifictor. During reserches on the experimentl plot of the lflf on green feed Sinsky ws cultivted. It ws sowed in the pure stte, the method of sowing ws ordinry, the technology of lflf cultivtion on green feed ws stndrd for the given region. The regime of the irrigtion ws studied on the exmple of the lflf of the second nd third yer of the life y different wys of wtering. At ll methods the gretest crop of lflf green mss ws provided in the second yer of life, nd for the third yer its efficiency hs shrply decresed, due to thin out the plnts. Within the limits of ech yer minimlly high crop of lflf ws formed in the first hy crop nd ws % from the sum for yer. It ws promoted y fvorle temperture conditions nd the longest period of its increse. A crop in the further hy hrvest goes down, it cn e explined tht y the repeted mowing of lflf the supply of plstic sustnces in root neck is exhusted y the end of vegettion. Only in the second nd third yer of

9 Alflf susoil irrigtion 121 the life efficiency of the fourth hy crop ws little it higher, thn of the third. It is explined to more lengthened vegettion period of the fourth hy crop. At the sprinkler irrigtion in the second yer during 4 hy crops hs een received the mximl productivity of 87,0 t/h. On the verge, t the sprinkler irrigtion for two yers productivity hs mde 79,4 t/h. Appliction of SSI in comprison with sprinkler irrigtion (DDA- 100 MA) llows increse of the lflf productivity. The gretest crop (95,0 t/h) hs een received on the plot with the highest pre-irrigtion soil humidity (80 % LH), it is on 8,0 t/h more, thn y sprinkler irrigtion. Decrese in pre-irrigtion humidity of ground to level of 70 % LH (LH Lowest wter holding cpcity) on the verge reduces the lflf productivity on %. The further reduction of redily ville moisture even more reduces the lflf productivity. Crop reduction is mrked y increse of distnce etween humidifictors. So, t the increse of distnce etween humidifictors from 1,5 up to 2,0 m, on the verge, productivity is reduced on 6,2-12,1 %. The design of humidifictor influenced on the formtion of lflf crop. So, t distnce of 2,0 m etween humidifictors, productivity of the lflf on green feed is more on vrint, where humidifictors from potter's pipes with nti-filtrtion screen re down nd up, thn with nti-filtrtion screen on the free lying clutches, on the verge in 5,1 t/h. Dynmics of verge mowing lflf crop, depending on different wtering wys is shown on fig Irrigtion 25 Productivity, t/h Hy crops SSI with the screen B=1,5 m B=2,0 m SSI with polyethylen wrpper B=2,0 m Fig. 2. Dependence hy crop verge productivity of Lucerne on green weight From the nlysis of clcultions it is possile to note, tht susoil wtering is highly effective wy of n irrigtion which ppliction gives sustntil growth of the lflf productivity on green feed. Among considered vrints of the susoil irrigtion the vrint t which humidifictors re mde from potter's pipes in dimeter of 50 mm with ntifiltrtion screen up nd down, nd distnce 1,5 m etween humiidifictors is optimum.

10 122 A. Akhmedov The clcultions ccording to io-energy efficiency of lflf cultivtion in Volg-Akhtuinsky flood plnt, t vrious wtering wys, hve shown tht ll vrints of the reserches re energy sving ecuse the reltion of the energy which hs een sved up in the iomss of crops, spent cumultive energy in ll cses exceeds one (t. 3). From t. 3 is cler tht on the lflf crops in the second yer of life the fctor of energy efficiency chnged from 2,53 up to 2,82. T. 3. Energy estimtion of lflf cultivtion with help of tests vrints Humidity of the soil efore wtering, % LH Totl energy expense, Dg/h Energy content in the crop, Dg/h Second yer Sprinkling(DDA-100 MA) Energy efficiency fctor , ,67 SSI , , ,82 2, , ,63 Third yer Sprinkling (DDA-100MA) , , , , ,7 SSI ,77 2,65 2,51 Thus, mong investigted wtering wys of lflf y tests vrints the highest io-energy efficiency hs SSI t mintennce of pre-irrigtion humidity gorge in 80 % LH. Thus the fctor of energy efficiency mkes 2,77-2,82. Discussion Now in conditions of growing deficiency of fresh wter, s primry, pln is rtionl use of wter resources, prcticl use of irrigtion in resources-sving technologies nd the most effective economic wys of irrigtion. The most ctul from ll the offered methods in present time is ppliction of susoil irrigtion. The prticulrity of the susoil irrigtion is tht movement of moisture in ground occurs not from top to down s t other wys of irrigtion, ut in rdil directions from n xis of humidifictor, siclly from elow upwrds - due to scending movement of moisture. Use of given irrigtion wy llows cretion of optimum wter-ir soil regime, keeping its structure nd ertion s improvement, to provide optimum for plnts cpillry humidifiction of soil. In this cse, the soil lnket hs the low humidity therefore the deep-rooted weeds perish, nd wter stocks in the soil, protected from evportion, get uniformity nd stility. Hence, mount of the wter supplied to crop irrigtion is

11 Alflf susoil irrigtion 123 reduced. The sic wter stocks re concentrted in rooting lyer of ground nd re rther esily regulted. The susoil irrigtion is expedient for introducing in wide scles in steppes, semi-deserts nd deserts where is shrp deficiency of wter; in mountins nd the foothill res sujected to irrigtionl erosion; on the grounds round of cities; t the comfortle settlements; lrge cttle-reeding complexes where it is possile to use economic - domestic nd lightning cttle-reeding runoff. By this method there is no dnger of environmentl pollution y runoffs nd growing production, ground nd ir y pthogenic microorgnisms nd helmints eggs. Efficiency of SSI is in dependence on the correct prmeters of the wtering technology - distnces etween susoil humidifictors nd depths of their stcking, optimiztion of irrigtion norms, speed of wter sorption, lengths of susoil humidifictors, nd hydrulic clcultion of humidifictors nd tuulr sprinklers is mde on the estlished wter expense. The susoil irrigtion opens the ig opportunities in utomtion of wter delivery process to the soil t simultneous stisfction of physiologicl need of plnts in wter during ll vegettive period. Lour productivity will ccordingly e rised t the generl decrese in lour expenses. The susoil irrigtion does not demnd dditionl energy, s it tkes plce t the sprinkling irrigtion, requires scrce mterils, such s metl much less nd t the sme time provides high efficiency of work. However, despite of contemplted intensifiction of scientific reserches, of successfully relized projects of lnd-improvement systems with susoil irrigtion, there re still lot of unsolved questions which cn impede the further increse of the res with this, undoutedly, progressive nd ecologiclly sfe wtering wy. Conclusion It is estlished, tht distriution of moisture fter wtering nd form of humidifiction contours t susoil irrigtion re determined, first of ll, y wterphysicl properties of soil, designs of humidifictors nd hydrulic regime of their work. The irrigtion norms hve ig positive influence on qulity of the soil lyer humidifiction. At the wtering with ig (600 m/h) norms of irrigtion wter sinks on the igger depth, thn with smll norms. However, smll irrigtion norms crete more uniform humidifiction on ll soil profile. For definition of wter expense in the humidifictor hed nd the specific expense of wter in humidifictors, depending on hed pressure nd wter durtion, the mthemticl dependences re resulted, llowing to count up supplying of irrigting wter for ny intervl t vrious pressures. Giving results hve llowed estlishing, nnul economic enefit t the susoil wtering is received due to decrese in expenses of energy in out 1000

12 124 A. Akhmedov MDg/h, in comprison with sprinkler irrigtion. Energy fctor t the SSI hs mde 2,50-2, Using of SSI systems for wtering of lflf on green feed in conditions of lluvil, lightly loms llows increse of this crop productivity on % t lower work expenses nd economy of irrigting wter on % in comprison with sprinkling irrigtion (DDA-100 MA). REFERENCES 1. G.V. Vedenypin. Generl methods of experimentl reserch nd processing of tests vlues.-moscow: Kolos, s. 2. B.A. Dospechov.Methods of the fields tests.-moscow: Kolos, s. 3. A.N. Kostykov.The foundtion of meliortion.-moscow: Gosselchoizdt I s. 4. V.N. Peregudov. Plnning of multifctor field experiences with fertilizers ndmthemticl processing of results.-moscow: Kolos, s. Askr Akhmedov, Doctor of technicl sciences, ssistnt professor t the chir of Technologies in mngement of nturl resources t Ecology Lnd Reclmtion Deprtment of Volgogrd Stte Agriculture Acdemy Universitetsky prospect, 26. Volgogrd, Russi. Tel. (8442) Received: Mj 05, 2008 Accepted: Juli 10, 2008