When the soil surface becomes sealed, infiltration slows or ceases and water begins to run off. Surface residue slows runoff and can increase the available time for infiltration by two to threefold. Soil residue, especially standing stubble, provides an added benefit in trapping snow. In western Kansas, moisture from snow can add 1.6", in an area where soil water available to plants from rainfall is only about 2.5" (10" rainfall during growing season and 25% efficiency). The University of Nebraska reports trapped snow can result in one to three inches of additional water being available for crop production, making snowfall an extremely valuable source of soil moisture. Tillage regularly results in significant soil moisture losses. Data from Colorado shows soil water losses from different tillage operations in Table 1.
Proper fertilization is essential for good grain and straw yields. Use soil tests to determine fertility plans for desired yields. Phosphorus is very important in winter wheat, as adequate fertility makes the crop more competitive with winter and spring weeds. Dual injection of anhydrous ammonia and phosphorus in 12-inch spaced bands is an effective pre-plant fertility method. Avoid top dressing when soil is wet or soil compaction will result. Ecofallow used with No-Till increases soil moisture.
The following data tables show advantages of tillage methods for increasing soil moisture to following crops.
|Years||Tillage System||Number of Tillage Passes||Annual Rainfall||Fallow Water|
|1931-45||Disk Conv. Till||5-7||15.8"||4.4" Storage|
|1946-60||Improved Conv. Till||5-7||16.4"||5.4" Storage|
|1961-75||Stubble Mulch Min Till||2-4||15.3"||6.2" Storage|
|1976-90||Min Till to No-Till||0-2||16.2"||7.2" Storage|
|Tribune, KS||144 lbs.||280 lbs.|
|Garden City, KS||163 lbs.||290 lbs.|
|Walsh, CO||118 lbs.||215 lbs.|
|Bushland, TX||87 lbs.||216 lbs.|