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[)~'2.3f)j6 peIwits, contour tillage will aid ma- terially in holding water that would otherwise run off. Terracing to supple- ment contour cultivation should be pl'!lcticed wherc practicable on group 3, although on finny fields this is impl'ac- ticable owing to the complex association of soils and to undulations in topog- raphy. Strip cropping on the contour, 01' field stripping where topography is irregular, using the more erosion-resis- tant crops in strips that alternate with crops less resistant, has proved to be helpful. We-cds must be- kept out of cropland since- they use large- quantities of moisture- that would otherwise be- available to the growing crop. Even in seasons of extremely low rain- fall, enough covel' may usually be pro- duee-d to control soil move-ment. Suffi- cient crop residue-s must be Ie-ft to e-ffect a de-gree of stabilization that will bal- ance the erosive forces of nature-. This means that if the crop is harvested, a stubble at least 10 inches high must be left on the ground (fig. 4). Field obse-r- vation indicates that de-nsity of stubble is of much greater importance- than height, provide-d the height is 10 inches 01' more. If fields are pastured, grazing must be controlled so that covel' is left to hold the- soil. This covel' must pro- tect the soil through the winte-r months and until there is sufficient growth from the- new crop to limit soil movement. Maintenance of an even cover over any graze-d field is difficult. Morcover, trampling by live-stock incre-ases wind erosion. Many farm people therefore question the advisability of any grazing of cultivated lands .except during the growing season, Fie-Ids that are- moderately to severe-Iy hummocked re.quire additional meas- ure-s before they can be cultivated safely. Leveling of hummocks, dunes, and fenoe rows by mechanical means lllay be nec- eessary. Ordinary hummocks and small dune-s may be leveled by listing during the blowing se-ason. Whe.n they are dis- turbe-d, wind erosion causes them to shift, and if the propel' type of lister furrow has been made the barren spots will usually hold all shifting soil and ap- proximate leveling will result. Relist- ing is usually necessary in order to mix as much undisturbed subsoil as possible with the loose sand in the furrows, thus minimizing the blow hazard. Vegeta- tion should be established as soon as possible. CLASS IV LAND Class IV lands are suitable for limited cultivation only. In the Baca County districts the- limitation is chiefly in the proportion of total area that can be cul- tivated. More intensive management and care are required than on class III. The class is made up of the medium- depth, moderately heavy soils (group 4), A and B slopes of the loamy sands of group 5, and the medium-depth sandy soils (group 55) on A slope-s that are not severely eroded. Class IV lands may be cultivated safely only in small areas, as a rule not more than 320 acres, distributed in land in permanent cover or otherwise stabilized. Areas selected for cultiva- tion will probably remain in cultivation since the climate makes it impracticable to cultivate occasionally and grow semi- permanent cover between periods of cultivation. In general, the cultivated acreage of these lands should be used to produce supplemental feed for live-stock and the land should be cultivated only if enough class III lands are not avail- able. On the moderately heavy soils (group 4), effort should be made to select land for cultivation to which additional mois- ture may be supplied by diversion and spreading of runoff water from adjacent areas. These soils range from clay loam to 10llJll in texture and conse- quently infiltration is slow. Cultivated areas should be terraced and contour farmed in order to secure the utmost utilization of rainfall (fig. 5). These hard lands have been considered the wheatlands of the county, and large acreages of wheat have been planted. However, owing to climatic limitations, crop failures recurred so frequently that erosion has taken huge toll (fig. 6). When moisture conditions and climate are favorable, good wheat crops may be produced, but such crops are theexcep- tion and cannot be depended upon. In order to stabilize agriculture Western and Southeastern Baca County Soil Conservation Districts, Colorado 13