Keep in mind that midwest and Canadian research will not translate directly to the PNW; however, the principals that they employ can benefit us -- don't discount their value too quickly. Some ideas work in our environment and soils.
The following are excerpts from NoTill Farmer website: http://www.no-tillfarmer.com/
No-Till, Right Rotations Store More Water
Scientists at the 102-year-old Agricultural Research Service Central Great Plains Research Station in Akron, Colorado, are in the 20th year of a major project determining which alternative crops farmers could use to eliminate — or at least reduce the frequency of — fallow fields.
Storing Precious Soil Water Is Key
Merle Vigil, an ARS soil scientist at Akron, gets farmers’ attention when he tells them that storing water in just the top inch of an acre of land — an “acre-inch” — is worth $25 to $30 an acre. Vigil, ARS agronomist David Nielsen and ARS soil scientist Joseph Benjamin made this calculation by using 10-year average crop prices in equations they developed to relate crop yields to stored water levels.
Four to six tillage passes to kill weeds result in a loss of 3 acre-inches of water over 14 months of fallow. Those six passes cost $24 to $48 an acre in fuel and labor costs.
“Adding that to the cost of water lost, that’s $99 to $138 from your pocket,” Vigil tells farmers.
The scientists have shown that using no-till practices in the conventional wheat-fallow rotation can increase net farm income. They have also shown that by combining no-till and no-fallow, farmers can capture much more of the precious 14 to 18 inches of rain or snowmelt that may occur each year in various parts of the Central Plains.
The idea is to store precipitation in the soil during the idle months,” Vigil says. “That was a good idea then, but today it is not economically or environmentally sustainable for most soils in the region.”
Fallow loses 65% to 80% of precipitation to evaporation. Besides wasting water, fallow causes a decline in soil organic matter, leaves soil susceptible to wind erosion and gives low economic returns.
Ways To Save Even More Water
The project has shown that no-till’s value for storing precipitation in soil can be enhanced by changing harvesting equipment to leave even more residue on the soil surface. This includes use of a stripper header. The stripper header removes just the head of grain, leaving the rest of the plant standing to enhance precipitation storage and erosion protection. Traditional combine headers cut off most of the plant stalk with a sickle and then leave the stubble short. [my comment: most of my life I have watched the relationship of snow and stubble height and concluded that 4" of stubble was all we needed to keep wind off the soil surface. That was wrong -- what should have been observed was that 4" dropped the velocity of the wind below the point where snow moved. The taller the standing stubble the less air movement along the soil surface, and less direct sunlight. This apparently, is reducing moisture loss another 1-1.5" over and above normally accepted DS techniques. References are being made toward this conclusion, but I haven't found direct statements through research projects to confirm.]
Also, the scientists have recently shown that skipping one or more rows — rather than planting every row of a crop — conserves soil moisture and improves crop yields.
“We proved the value of stripper-header harvesting and skip-row planting in ancillary experiments and then made them part of the ACR project in recent years,” Vigil says. [my ?: does this mean that you need to maintain stubble height in skip row? Other sites are indicating that, for the growing crop the stubble needs to be flat to minimize sunlight intercept. Statements like, spindly stalks, and reduced tillering are connected to amount of direct sunlight the crop receives -- more is better.]
Adds Nielsen: “Including crops such as millet and triticale, grown for forage instead of grain, reduces the risk of total crop failure from a lack of rainfall during the critical growth stages of grain crops.”
He has found other ways to reduce the risks of drought, including estimating soil water in the spring to see if there is enough to warrant skipping fallow.
[my commentary: removing fallow from our rotations was a prime reason for us to look at DS 30 years ago. The problem in the past has been the low $ value of all our alternatives to wheat. That may be changing. If so, all we have to deal with is changing 100+ years of mindset of "wheat is all there is".]
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