m j o crwvib J2,>j.)pjLrv»-A/vvA/C[t^ v-^nJlX/N /vvAAr^^cnXv/>^v«Q : vArvitsvwwvva iL\i'l-vs^v)i/w^%v3r -^XoXv^rx^ ,'2> ^-^^ii^J^^^^ Book • ^1 7 UNIVERSITY OF WYOMING, Agricultural College Department. WYOMING EXPERIMENT STATION, LARAMIE, WYOMING. NOVEMBER, 1899. Some Experiments With Subsoiling. BY B. C. BUFFUM AND W. H. FAIRFIELD. Bulletins will be sent free upon request. Address : Director Experiment Station, Laramie, Wyo. Monograph s '^^ ^ I Wyoiig AgrMM Mmt Slatloi. UNIVERSITY OF WYOMING. BOARD OF TRUSTEES. Hon. OTTO GKAMM, President, Laramie 1903 GRACE RAYMOND HEBARD, B.S., Ph.D., Secretary, Cheyenne.1903 HENRY L. STEVENS, B. S., M. D., Laramie 1903 Hon. TIMOTHY F. BURKE, LL. B., Vice President, Cheyenne. .1901 Hon. JOHN C. DAVIS, Treasurer, Rawlins 1901 Hon. NATHAN S. BRISTOL, Casper 1901 Hon. MELVILLE C. BROWN. Laramie 1905 Hon. JOHN A. RINER, Cheyenne 1905 Hon. S. CONANT PARKS, Ph. D., Lander 1905 Hon. THOMAS T. TYNAN, State Supt. Public Instruction. .Ex-Offlcio President ELMER E. SMILEY, B. A., D. D Ex-Officio AGRICULTUR.VI- COMMITTEE OP THE BOARD OP TRUSTEES. H. L. STEVENS, Chairman Laramie OTTO GRAMM Laramie M. C. BROWN Laramie ELMER E. SMILEY Laramie PRESIDENT OF THE UMVERSITY OF WYOMING. ELMER E. SMILEY, B. A., D. D. STATION COUNCIL. E. E. SMILEY, B. A., D. D Director B. C. BIJF FUM, M. S., Vice Director, Agriculturist and Horticulturist A. NELSON, M. S., M. A Botanist E. E. SLOSSON, M. S Chemist W. C. KNIGHT, M. A Geologist C. B. RIDGAWAY, M. A Physicist and Meteorologist G. R. HEBARD, M. A., Ph. D Secretary W. H. FAIRFIELD, M. S Wyoming University Experiment Farm The Horticulturist in Charge, Wyoming University Experiment Grounds ^; Some Experiments With Subsoiling. BY B. C. BUFFUM AND W. H. FAlRFlKf.D. The natural requisites for farming,- are soil, water, air, heat and sunshine. With one exception these natural bless- inut water is never still. In seeking its common level, the sea, it runs otf the surface of the bind, or see}(s thiough the u]>j)er layers, escaping from be- low and that which is retained for a time by the soil is be- ing continually dissi])ated into the air as invisibh^ vapor. In our dry climate the e\ ai«)iation is so great that five or ten times as much water as comes to rhe eaitli in a year by rain would be lost by this process alone. Any jiractical jilan then of saving as much moisture as |)ossible for the use of cro]»s is of great im]>ortance and value. Tillage consists of stirring the soil and is as old as agri- culture. Its etf(^ct is somewhat complex. It breaks up the soil admitting aii". without which plants can not grow. It loosens the soil so it becomes suitable for planting the seed, as well as for tlu^ dev'elopment of ])lant i-oots and for the absorittion of watei'. brought to it by rain or ii-rigation. It disintegrat(^s the soil particles continually unlocking and n)aking available^ to the ]>lant new stores of ])lant food. It (h^stioys W(vds. Breaking u]> the surface foinis a blanket which ]ii'events the raj)id loss of water by eva]»oration. Is it enough that we shall cultivate the surface of the earth, or 2 Wyoming Experiment Station. shall we find it profitable to extend tillage deeper into the hitherto undisturbed subsoil? Subsoiling is stirring- the earth below the region of the plow. For convenience we speak of the first eight inches of soil which may be turned over in plowing as the surface soil and all below this as the subsoil. Plowing turns the surface soil bottom side up. Subsoiling does not change the position of that part of the soil, but it breaks up and stirs the ground below the ordinary depth of plowing. This n)ay be effected bV a spur or prong attached to the plow which breaks up the soil at the bottom of the fufrow, or it may be done with a separate implement to be drawn along through the soil beneath the bottom of the furrow after the i»low, to stir the ground to greater depths than can be done with a small attachment to the ordinary plow. This implement is called the subsoil plow and usually consists of a mole or a more or less flat piece of iron pointed at one end and attached to the beam by a strong flat vertical blade. When drawn through the soil in the bottom of the furrow left by the plow this implement can be made to break up and stir the subsoil to a depth of fiom one to two or more feet. The advantages claimed for subsoiling are that it makes more room for root development, and enables the plant to extract food and moisture from a greater area, and that by loosening up more of the soil its capacity for absorbing and retaining moisture is increased. By the absorption of greater amounts of moisture in winter and spring it is sup- posed that subsoiling ]>rovides against summer drouth. It is reasonable to suppose that this is what would happen and the many favorable reports on subsoiling from humid and semi-arid regions indicate that loosening the lower lay ers of soil is a valuable way of conserving moisture for those regions. Before discussing the efl"ects of subsoiling in Wy- oming the dift'erences between a truly arid region and one l>^onie E.rpcr'nnents With Stibsoiling. which is only semi-arid should be briefly pointed out. Places where the annual rainfall is less than fifteen inches are gen- erally called arid. The air is dry; the evaporation is grt^at; the rainfall is not suttlcient to niatui'e cultivated crops. In the semi-arid region the rainfall is mort' than fifteen inches and may be enough to mature i)rofitable crops if the moist- ure can be stored u]) in the soil and saved until the crop can make use of it. In ^^'yoming the conditions are truly arid unless it be in the extreme northeastern portion of the state. There is little precipitation during the fall and winter, so very little moisture escapes by running directly off the sur- face of the land. If, then, subsoiling is not necessary to in- crease the holding ca] acity of the soil, and absorb water during time of extra sui)i>ly. will it save more of the water which may be a]»i>lied artificially during the growing season and will this and other advantages make it ])rofitable to go to the extra ex]>ense of such tillage in our state? To solve this question we have been experimenting with subsoiling for three years and this bulletin is ])uhlished to report the results obtained. The experimi'ut was con- ducted in the same manner on the several ex]»eriment farms in the state. Unfortunately the records of the Land(M- farm were lost in transit, and the publication of this bulletin has been long delayed with the hope they might be found. The soil of the Lander and Sundance farms is almost identical, the altitude of the two places is not far different and while the experiment in subsoiling was only carried out one sea- son at Sundance, a comparison of the results obtained would be highly interesting. The climate of Sundance is serai- arid or sub-humid, crops being raised without irrigation, while that of Lander is arid and no crops are raised without irrigation. A comparison of the results at these places would give more trustworthy evidence of the difference in value of subsoiling under such conditions of climate and farm practice. The experiment was begun in the spring of 189G and ear- Wyoming Experiment Station. I'ied out that year at Laramie, Lander, Sheridan, Sundance and ^Vheatland. In 1897 the cropping was repeated on tlie same land at Laramie, Lander and Sheridan, and in 1S!>S, at Laramie only. PLAN OF THE EXPERIMENT. Following i.s an <»utline of tlu^ instructions for subsoiling which, with slight modifications for each locality, were fur- nished the farm suiierintendents in the spring of 1896 — This ex])eriment is to be carried on alike on each of the farms. Select a suitable acre plat. Plow the land over the whole }>lat the same and let all other o]>erations such as harrowing, etc., be the same for all parts of the plat. Sub- soil thoroughly one-half of the plat. Mark carefully and pernmnently the line where the subsoiling sto})s. Divide the i)lat into four equal parts so one-half of each fourth is (»n the subsoiled iiortion and one-half on the part merely i)lowed. Ljion the first fourth acre i)lant oats. Lpon the second fourth acre plant potatoes. L})on the third fourth acre jdant wheat. Divide the last fourth into two jiarts and plant beets on tlit^ one and coi-n on the other. Treat the crops on the plowed and subsoiled land the same throughout the season. Kee]» careful notes of any variations on the two parts of each plat. When you harvest each cro]t cut out a strip six feet wide along the line on which the subsoiling stops, casting out the cro]> from a strip three feet wide on each side of this line, which part is to be taken no account of in figuring up the yields on subsoiled land or land not subsoiled. This is iujportant as the effects on the ground treated or untreated will reach across the line some distance. Measure the area in square feet occupied by each crop to be used in figuring ui» the yields. In the case of rowed *S'o?Me E.Tperiments With ^nbsoiling. crops, allow for the number of rows at their distance apart and take the length of row on treated and untreated land. This experiment will be repeated upon the same ground for a number of years to determine the effect of subsoiling on soil and crops — . In 180S some additional land was subsoiled and on one plat of oats covering one-half acre an accurate measurement was made of the irrigation water used. In 1897, the next year after the land was subsoiled for this experiment, the Physicist made a study of the moisture content of different soils which was published in Bulletin No. 35 of this Station, a resume of which is used in this report. Results of the Experiments. Plants of different kinds act very differently when grown on subsoiled land. The effect on a crop of loosening the soil to a depth greater than by ordinary plowing is also very different on diffei'ent soils and under varying climatic conditions. Our experiments were carried out in widely sep- arated parts of Wyoming and with the more important crops raised in each section. Again there are often accidental variations which throw doubt on the value of an experi- ment and where possible the work has been repeated more 6 Wyoming Experiment Station. , than one season. The conclusions reached have been care- fully drawn and we believe the results of these experiments are worthy of consideration by our farmers. The soil on the station farm at Laramie contains con- siderable gypsum and lime carbonate, is quite sticky when wet and becomes firmly compacted below the plow. The land selected for this experiment had been cultivated for a number of years. It was plowed about eight inches deep and one-half the plat was subsoiled to a depth of fourteen to sixteen inches in April, 189fi. The ground was so hard that four horses were required to pull the subsoil plow and if larger areas were to be treated six horses would be necessary. The land was not again subsoiled but the dif- ference in the yield of crops produced was observed for three seasons. This shows the lasting effects of subsoiling and the return which may be expected from one such treat- ment, and throws light on the absorption and retension of water through the entire year. The second year there was a slight difference in the depth of the plowing on the two portions of the plat. Where the land had been subsoiled the plow sunk one to three inches deeper than on the plowed portion. On the other station farms in the state the plowing and subsoiling was done in the same manner as at Laramie, At Sheridan the soil is clay underlaid with true hardpan. It is not known to what extent this hardpan was broken up by the subsoil plow. At Wheatland the soil conditions are much the same as those at Laramie. At Sundance the soil is deep, contains gypsum and much of the subsoil consists of red shale which is not tenaceous but comparatively easy to work. The average rainfall is nearly ten inches at Laramie;, about the same at Wheatland, nearly fourteen inches at Sheridan and twenty inches at Sundance. At Laramie and Wheatland from fifty to sixty percent of the total annual precipitation falls in the growing months of May, June,. Some Experiments With Suhsoiling. Julv and Aiiffiist. The greater amount of precipitation at Sundance and the fact that the land was not irrigated un- doubtedly accounts for some of the difference noted in the effects of subsoiling between the Sundance and other farms. Subsoiling for Grain Crops. Table I. gives the effects of subsoiling on the yields of wheat. Though the difference was not great, the yield from the subsoiled land was less than that from the land only plowed, at Laramie, the year the subsoiling was done. The second and third years there was a slight increase in yield from the subsoiled land. The increase in the yield of straw is greater in proportion than that of grain. This condi- tion would be expected as the increased feeding area of the roots and other conditions favoring rank growth would produce more straw and less grain where the growing sea- son is short. The reason for this is indicated in Wyoming Station Bulletin No. 37 on the "Stooling of Grains." It is a general law that under adverse conditions plants strive to mature seed in order to reproduce themselves. Under these conditions then, grain will mature earlier and pro- duce more seed in projwrtion to the rest of the plant than where everything is favorable to long continued growth. Table I. — Subsoiling for li/ieat. Yields in Pounds per Acre. Laramie. Sheri- dan. Wheat- land. Sl'NDANCB. Straw and Grain Grain Grain. Grain. Straw and Grain. Grain. /Subsoiled Fi-Y—^!°r-:: :::::::: ' Loss 2(127 !»43 997 3000 2550 l(iI4 3920 3441 1440 1160 r>4 450 112 480 280 Second i Subsoiled 2174 1S94 901 S76 2700 1950 280 25 750 ( Gain 2170 2127 908 833 43 85 1 Wyoming Experiment Station. The increase in yield of wheat at Laramie the second and third years on the hind which had been subsoiled is but little more than enough to balance the decrease the first season. At Sheridan there was an increase in yield the first year of seven and one-half bushels and the second year of twelve and one-half bushels on subsoiled land. At Wheatland and Sundance the increase on subsoiled land was small but was over twice as much at Sundance as at Wheatland. The results with oats are given in Table II. The length- ening of the season for oats by subsoiling was more marked than with wheat. At Sundance the oats on the subsoiled portion of the plat seemed to be making better growth dur- ing the first ])art of the season but, when harvested. Super- intendent Hoyt reported a smaller yield than was obtained from the land treated in the ordinary way. At Laramie the oats were later in reaching maturity on the subsoiled land. It may be stated that late varieties of nearly all crops, if not interfered with by frost, produce heavier yields than th(»se which require only a short season in which to ma- tui-e. Lengthening the growing season for the same variety would be expected to increase the yield, but at the high altitude of the land over a large part of Wyoming the time between late and early frosts is comparatively short and earliness in ripening is a most important factor. There was a slight increase in yield of oats the first two years, but the third season the decrease in crop was almost enough to balance the gains of the first two seasons, though whether or not the efi^'ect the third season was due to subsoiling may be questioned. At Sheridan there was a loss of seventy pounds more of oats the first year than was gained the second year by sub- soiling. At ^Mieatland there w^as a small increase on the subsoiled land, but the variation was small, probably not more than would be obtained on any two plats, though treated exactly alike. To all appearances the yields of oats ^onw Experiments With Huhsoiling. 9 were not luaterially influenced at any place by subsoiling the land. Tablp: II. — Subsoiling for Oats. Yield in Pounds per Acre. Laramie. Sheri- dan. Wheat- land. Sundance. Straw. Grain. Grain. Grain. Straw. Grain. 1 Subsoiled ) Plowed 4;J90 3S98 1520 1345 •5070 3360 1898 1014 1960 2224 512 648 First Year 492 175 290 184 356 — V Loss 136 Second (Subsoiled 'WyS ;«7s 1345 1194 2700 24S0 Year. ( Gain 177 151 220 Third / Subsoiled. ... .... ) Plowed . . . 8(i4r> 4445 1302 1526 800 224 'Loss. Because of the high altitude with the accompanying short seasons and cold nights, corn is not grown at Laramie, so barley was planted on one i»ortion of the subsoiled plat at this place and corn was grown at Sheridan, Wheatland and Sundance instead of barh^v. The results with barley and corn are given in Table III. It is doubtful if any ef- fect on the yields of barley one way or another can be tracpd to the subsoiling. The first year there was less straw and more grain on the subsoiled land. The second year this was reversed, there being more straw and less grain where subsoiled, and the third year there was aproximately no diflereuce in the i)roductiou of straw, but there was quite a decrease in the yield of grain. Subsoiling for corn did not pay at the siib-stations ex- cei>t at Sundance where a good increase in yield was ob- tained. At Sheridan there was quite a large decrease in yield of corn the first season, and no difference the second year. Sui>erintendent Lewis reported that the corn did not mature as well on the subsoiled land. The first year the estimated yield on the subsoiled part of the plat was 10 Wyoming Experiment Station. thirty bushels per acre, and on the land not subsoiled thirty- five bushels i>er acre. Ten per cent, of the corn on the land merely plowed ri]>ened thoroughly, while all the grain from the subsoiled portion of the plat was soft and immature. The second season fifty bushels of mature and thirty bushels of soft grain per acre were harvested from each portion of the plat. To com])are with others in the table, these yields have been reduced to pounds by using the weight of seventy pounds per bushel for corn in the ear. At Wheatland during the season of 1896, the supply of water for irrigation was somewhat limited, and if the crops suft'ered for water, as they probably did to some extent, those on the subsoiled land would be expected to have the advantage. Mr. ]M. R. Johnson, the superintendent, states that all the crops made a better growth on the subsoiled land, that they seemed to withstand drouth better, and that the quality as well as the quantity of the product, indicated beneficial effects from subsoiling. The corn gave an in- creased yield of 80^ pounds ]»<'r aci'e on the subsoiled land. Table III. — Subsoiling for Bat-ley and Corn. Yield in Pounds per Acre. Lar.\mie. Shkri- UAN. Wheat- land. Sun- dance. Barley. Corn. Corn. Corn. Straw. 1 Grain. Grain. Grai^. Grain. / Subsoiled „. ,, ) Plowed First Year, ^'^i^ 2044 1 1325 2989 1 r292 2100 24r)0 3590 2227 3008 2416 — 33 45 - 350 363 592 /Subsoiled Second J Plowed 4(102 4123 1479 1668 :i500 3500 1 479 ' Loss — ! 189 ^Subsoiled Third j Plowed 2169 2175 527 752 6 225 I Loss Soine Experiments With Suhsoiling. 11 Subsoiling for Root Crops. The fact that deep soils are favorable for the growth of roots is recognized everywhere, and as would be expected subsoiling produced more marked effects on the yields of root crops than it did on grains. In Table IV., reporting the results with root crops, it will be seen that in every trial there was increased yield from the subsoiled land, and in some instances there are important gains. The lasting effect of subsoiling is well brought out in this table. All the tables show that, at SlKM'man, where the experiment was cari'icd out two years, and at Laramie where results w'ere obtained three seasons, the beneficial effect of subsoil- ing is greater the second year than it is the season the sub- soiling is done. This indicates that it would be advisable to subsoil in the fall rather than in the spring. The third year the soil has probably become compacted again so the effect is much less than it is the first two seasons. Table IV. — Su^soi/m^ for Root Crops. Yield in Pounds per Acre. L.^RAMIE. Sheridan. Wheat- land. Sundance. o 2 o a. cs .9- 'c o O 0. o o a. CO o 2 o PL, m 1 Subsoiled First Year.. Plowed 8695 8380 315 i28.-iS| lasoo 10620 t2(iOO 2425 2151 274 8302 8009 293 S224 : 17161 6960 1 14S41 ( Gain 223.S 1260 1264 2320 c^^„„^ \ Subsoiled -" lSr^.-::::: 3672 2620 12893 IIMS 28700 24795 1052 1250 3905 ( (jam ()940 6865 5450 4522 75 1 928 POTATOES— At Laramie the jiotatoes planted the first year failed to grow because the soil was too dry. The second and third years the stand was poor and small yields were obtained, but there was a good increase of crop on the sub- 12 Wyoming Experiment station. soiled land. In Table IV. only the yields of potatoes which were of sufficient size for market are reported. The pro- portion of large and small tubers on the two kinds of ground and the increase in size on the subsoiled land is of interest. Table V. gives the yields of large and small potatoes, the percent marketable and the weight of the largest twelve tubers from each portion of the plat at Laramie in 1897 and 1898. The difference in yield in 1898 is small and there was practically no difference in the size of the pota- toes, indicating that little effect on this crop was produced by the lower soil having been loosened up three years be- fore. The second season after subsoiling, however, there was not only a large increase in the yield, but in the size of the tubers as well. 'I'ablk V. — ■ Effect of Suds<7i/ino- on Size of Potatoes. at Laramie, Wyo. 1897. 1898. Yield. Percent Market- able Weight of largest twelve. 5.1 4.5 Yield Percent. ^'^V^^' Large. Small. Large. Small. able. largest twelve. Subsoiled Plowed :{(i72 2(520 1552 ItiCO 70. :i (il.2 9.1 "1)040" (i8()5 75 2417 2212 205 74.2 75 . 5 4.() 4.6 Gain 1052 802 0.(i At Wheatland the subsoiling ]»roduced little effect on ])otatoes. The incrcnise in yield of marketable jxitiitoes was only 274 pounds. Of the entire cro]) (12.8 ps^rcc^nt were marketable on subsoiled Innd, and on the land not sub- soiled the marketable tubei's were 08.fi ]>er cent of the whole crop. At Sliei-idan and Sundance the small potatoes were not re]K)rted, but at Sheridan tlu' largest 12 tubers from suhsoih^l land weighed six and om^-half pounds and from ])lowed land six ])ounds. SUGAR REETS — Subsoiling gave satisfactoi'v increase in yic^lds of sugar beets at every jilace except Sheridan. At Some E.iperiineiits With Hubsoiling. 13 Laramie the increase iu size of the beets is worthy of special mention. Not only were the hirgest twelve very different, from the two plats, but the average size of the roots was much larger on the deep soil. In 1897 the largest twelve roots from the subsoiled plat weighed nineteen pounds and from the }>lat not subsoiled twelve roots weighed eleven pounds. In 1898 the dift'erence was less. Twelve of the largest beets from the subsoiled plat weighed in the aggregate seven and one-half pounds and from the plowed land six and one-half pounds. Analysis of the beets showed slightly better results from the land not subsoiled. Beets from subsoiled land contained 19.7 percent sugar and had a jturity of 88.2. while those from the adjoining ]tlo\\(' of 1897. tlie second year aftcM' subsoiling. SUBSOILING, IRRIGATION AND SOIL MOISTURE. Tln^ subsoil jdats were suuill, and as it was necessary to treat the croi»s alike on borli parts of tlie ])lat, it was im- })ossible to measure the amount of water used on each ])or- tion. An experiuKmt was carried out with different amounts of watei- on the j)otatoes growing on the subsoiled land in 1897. Measurements wtM'e made of the total amount of water used on the i.lat. one half of which was subsoiled and also on anotluM- subsoiled ])lat, and we ar<^ able to com- pare these measurements with the amount of water us(^d on other fields. During the season of 1897 the Physicist made a series of moisture determinations on the diff'erent soils and ])ublished the results in Bulletin No. :i5, a resume of wliicli is shown in the accompan.\'ing diagram. These observations i^nable us to diaw some conclusions in relation to the soil moistui'e and the usi^ of ii-rigation water on such dee])ly tilled soils at Laramie. In 1890 the barlev, oats and wheat, were iriigated twic<\ *See Wyoming Station Bulletin No :%. Page J!(" 14 Wyoming Experiment Station. on the acre of laud one-half of which was subsoiled. At the first irrigation on July 2, enough water was applied to cover the land 11.4 inches deep and at the second irrigation enough water was applied to cover the land 6.12 inches deep, or a total depth for these crops of 17.52 inches. The precipitation for the year was 10.75 inches of which 4.75 inches fell during the months of May, June, July and August. This gave a total of 22.27 inches for the growing season or 28.22 inches of water for the year. The same year wheat and oats on other fields received enough water by irriga- tion to cover the land to a depth of 14.88 inches, and barley received 14.52 inches of water, showing that enough more water was applied to the acre, one-half of which was sub- soiled, to cover the whole plat three inches deep. If this. was due to the effect of subsoiling it means a requirement of six inches more water on the subsoiled land. Unfor- tunately the record of measurements of water on the sub- soiled plat was broken, so it cannot be reported for 1897, but in 1898, trustworthy measurements were secured. The wheat, oats and barley were irrigated twice. On June 24, enoug^h water was applied to cover the land 11.52 inches deep, and July 18 enough water to cover it 9.12 inches deep or a total of 20.64 inches. Including the rainfall, the land received enough water during the growing season to cover it to a depth of 25.22 inches, and in the year 28.26 inches. It is not possible to draw conclusions in regard to the effect of the subsoiling on this plat in 1898, as other crops of the same kind received varying quantities of water, some more and some less than this amount. On another plat, however, which was subsoiled in the spring of 1898 and planted to oats, the amount of water used in ii*rigation was very large. The land was irrigated twice. At the first irrigation on June 27, enough water was used to cover the land 30.84 inches deep, and all of it was absorbed by the soil. At the second irrigation, July 11, enough was used to cover the land 13.44 inches deep, — c 5 = < o CO " Some Experiments With Subsoiling. 15 making a total for the season of 44.48 inches, or 3.69 feet. Includiug the rainfall, this gave a depth of water brought to this laud in the year of 51.91 inches or for the growing season of 48.47 inches. The amounts of water used on other [>lats of grain in 1898, was 1.90 feet on one held of oats, 2.58 feet for oats on sod, 1.55 feet for oats and cultivated grain, 2.70 feet for one plat of barley, 1.74 feet for one plat of wheat and oats, and 3. 03 feet for one field of wheat, which was irrigated three times and given an unusual amount of water. The illustration of five feet of soil on the Experiment Sta- tion is made from a photograph taken one year after the subsoiling was done. The upper eight inches of dark soil is the portion turned over each year by the plow. The next six or eight inches of subsoil shows the effect of having been loosened by the subsoil plow, leaving it porus. On the native plains the soil below the first one or two feet may not have been wet for ages, as the natural rainfall is not suflflcient to wet more than the first few inches of sur- face, and there is practically no difference in composition between the surface and subsoil. Breaking up the layer which is compacted by the plow in the bottom of the furrow gives the water a new reservoir below the plowed land and affords a means of escape by seepage, which would account for the large amounts necessary to soak it up when irrigated and perhaps also for easy dissemmination and loss of the moisture afterwards. In 1898 the potatoes on the plat, one-half of which was subsoiled, were divided into two parts. One part was ir- rigated twice, using only a small amount of water each time and the other part was irrigated three times. Those irrigated twice received enough water to cover the land 2.04 inches deep on July 28, and 1.56 inches deep on August 4. The ones irrigated three times received the first irriga- tion on July 7, when enough was applied to cover the land 10.20 inches deep. At the other two irrigations they were -(2) 16 Wyoming Experiment Station. given the same amounts as the potatoes which were irri- gated but twice. The results are given in Table VI., which shows the amount of water applied and the yields on land subsoiled and not subsoiled. Table VI. — Potatoes with Two and Three Irrigations on Subsoiled Land. Laramie, Wyo.,1898. Total amount of water applied. Inches. Yield on land plowed Pounds. Yield on subsoiled land. Pounds. Average yield. Pounds. \Veight of largest twelve plowed. Pounds. Weight of largest twelve Subsoiled. Pounds. Irrigated twice Irrigated three times 3.C i;i.8 4972 8759 5290 8.591 5131 8675 3.6 5.6 3.9 5.3 10 2 3787 3301 :i544 2.0 1.4 This shows an increase due to the increased amount of water applied, of over seventy-six percent on plowed land, and sixty-two percent on subsoiled land, the average in- crease being about sixty-nine per cent. The fact that in- creased water applied in irrigation did not increase the crop as much on subsoiled land as on the land which was plowed is in favor of the subsoiled land as it indicates that the crop actually needed less water to produce the same yield. This may be true, as the variation is small and may be accidental, and it is possible and i^robable that more water was actualh' absorbed by the subsoiled portion when irri- gated. It is unfortunate that we are not able to make a like comparison the first and second seasons after subsoil- ing. If moisture comes to the soil during any part of the year, the friends of subsoiling claim that it is retained and made more available to the crop. The study of the moisture in the soil of the ditferent ])lats at Laramie in 1897, which was made by the Department of Physics, does not seem to bear out such statement. The accompanying chart illustrates the difference in moisture content of the soils on sod land, on land which was plowed in the usual way and on the sub- soiled land. The determinations of moisture were made iconic l'J.ri)critiiviits WitJi Siihsoilhifj. 17 daily and these have been averajjed for each month. The saniph'S were taken to tlie depth of one foot by driving tubes about one inch in diann^er into tlie soil. On the loose ground some of the soil might be diiven down in front of the tube instead of entering it, but the sam]>les were carefully taken and no elTcct of the kind was noted. The vertical black lines in the chait iipreseut the average jter- cent of moisture in tlie soil which is also (expressed in iig- urcs at the to]» of each column. The last three columns at the right re]trcseut the average j/ercent of moisture for the summer. The lowest moisture content observed was 2.52 per- cent in sod land, Sei>teniber 24. The highest percent observed was 22.25 on the land j)lowed but not subsoiled and imnxdiatcly after irrigating it. The amount dro])])ed to 19.7 percent the second day, and to 15.7(5 ]>ercent the third day. (^n the subsoiled jiart of I he jilat after irrigat- ing the percent was 21.15 the first day, 21.7(1 the second day, decreasing to 1(5.28 the third day aftei- apjtlying the water. There is little ditfei*ence in the average moisture of the sur- face soil on th(^ ].'lowed land and that subsoihd, but what dilference there is shows less moisture on the subsoiled land throughout the summer. Thes(> facts indicate that more water was needed at Laramie to in-igate sul)soiled land and less of it was retained by the surface soil for the use of the i)lants growing thereon. It is possible there was more water in the soil below the deptli of these sam])les on the sul)soiled jtlat, but the ditferenct- was not great enough to produce markf^l effects on the crops. At Shei'idan the Ku]Huintendent states that mVu'e water was re(iuired at the first ii-rigation and less at the second on the subsoiled land. At Wheatland the crojis seed by the subsoiled land wln^n it was irrigated. a; 1 5 ^ ^ O CO lie > 1 j:5 lA J o K 5^ <0 ir- 3^ 1 ■i 5 5^ ^^^^_^_|_ ^ (W < K "»^ en 5 ^ 6 o 1 > ~ VB JO O f ^ -Ti 5 <-Y 75 ^ 5 J p5 i ^ ^ome E.Tperiments With ^uhsoiling. 19 DOES SUBSOILING PAY ? The test of the advisability of any operation on the farm lies in the final result measured in dollars and cents. Sub- soiling,- is an expensive operation which more than doubles the ordinary cost of ivreparinfj^ the land for the crop by plow- ing. The cost of snbsoilinfj- will vary with the condition of the soil and the price of labor. The cheapest it could hi' done on lar^e areas, and thoron<»hly done as in these experiments, would be at a cost of not less than three dol- lars ])er acre, ^^'here w<^ broke up the subsoil to a depth of fourteen to sixteen inches, on small plats the expense was five or six dollai's per acre. Unless it increases the yield, improves the quality and therefore the value of the croj), or reduces the expense of pi-oducin^ it, or requires less water so the same sup]>ly will irrif^ate more land, the practice of subsoilin*;- cannot be i-econimended as one to be adopted on the farm. jReferrinji- to Tal)l(^ I. in which tlic yields of wheat on sub- soiled land and on land prcjfai'cd in the ordinary way are com]>ared. it is evident that the ai-cumulated increase for three seasons at Laramie would not ])ay the exj)ense of one subsoiling. At Shei'idan the increast- of 450 pounds of wheat jter acre the fii'st y(^ar and T-IO pounds the second due to subsoiling would give a total value of twelve dollars jier acre more from the snbsoiled land. If the subsoiling cost four dollars per acre more than the ordinary expense of plowing-, the margin of j)rofit is larg-e (Miough. Even though we allow for a considerable increase in yields the second year at Wheatland and Sundance, snbsoiling would not ]>ay foi- wheat in these localities. The results with oats as given in Table II. do not show any marked or unifoi-m improvement in the crop. So far as our experiments may be relied upon as showing the true effects of subsoiling in this state, the indications are that it will not pay to so prepare the soil for oats. The same 20 Wi/uiniii(j Experiment Station. statement may be made for barley and corn nnless it be at Sundance, where the increase the first year and the proba- bility that there would nlso be a like increase in the crop the second year, indicate that subsoiling for corn might pay in that region. Subsoiling for root crojts did not give a return the first year at Wheatland, large enough to pay the cost, though the (piality of the crop was im])roved and the increase the second season might leave a i)rofit. At I.aramie the in- crease in the potato cro]) the second year (see Table IV. page 11), would be worth .fl0.50 to |i;i.O() at the local mar ket i)rice. On the Sheridan farm the increased yield of potatoes the first year was worth from |11 to $20, and at Sundance from |0 to fl2, depending on the market price. The value of sugar beets for stock food would make the in- creased yields from subsoiled land at Laramie, Sheridan and Sundance profitable. As a rule we beliine that sub- soiling for root crops will bring a ]»rofitable return. Whether or not subsoiling will ])ay de] tends largely on local conditions and the kind of crop. Beforv ado])ting so expensive a system of tillage the farmer should satisfy him- self in regard to whethei- it will bring a profit on his land by making small trials. Our results can not be said to in- dicate that subsoiling in regions which depend on irrigation will materially assist in saving the moisture or make ir- rigation less necessary. It is tiue that subsoiling ap- jjarently mitigated the effects of drought scunewhat in Wheatland, though the increase in the value of the cro]» was not sufficient to ])ay for the ex]>ense incurred. It is ])ossible that, where w'ater for irrigation is scarce, and other conditions are favorable, subsoiling might make the water which is available go farther in maturing a croj), though we have been unable to prove any valuable saving of moisture where the subsoil is nmde porus. 8o?n€ Experiments With Suhsoiling. 21 SUMMARY. The expense of Hubsoiliii"; to depths of sixteen or eighteen inches is from three to six dollars per acre. Subsoiling is probably more valuable in semi-nrid or humid regions than where irrigation is practiced. The effects of once subsoiling the land may continue for three or more years and under our conditions are more ap- parent the second season after the subsoiling is done than they are the first. If subsoiling is to be practiced, we recommend doing it in the fall. Subsoiling does not produce a uniform effect on the grains. Under certain conditions it may pay for wh(^at raised by irrigation. We have not found it profitable for oats, barley, or corn. Grain takes longer to mature on subsoiled land. At high altitudes where the season is comparatively short it is doubtful if subsoiling for grain is advisable. The quantity and quality of root crops are greatly im- proved by subsoiling the land. Subsoiling can be generally recommended in this state for potatoes. Under our conditions subsoiling has increased the amount of water needed to irrigate the land and apparently is of little value in conserving moisture. However, if no water could be applied by irrigation during the summer, the fill- ing with moisture in the winter or spring by rainfall or ir- rigation of the reservoir formed by subsoiling, would be beneficial.