There are very few rules that apply to successfully starting a crop, whether under cultivation or by direct seeding. a--place the seed where it can imbibe moisture when ground temperature is conducive to seed germination. (Traditional thinking meant that this required seed-soil contact as paramount. New thinking is that soil humidity is paramount and seed-soil contact has importance but is secondary) b--place the seed so the sprout can reach the surface, and the root can gain purchase in moist soil. Those are the basic rules.
With the root in moist soil and the shoot receiving light the plant becomes a manufacturing facility. Take either the light or moisture away from the plant and manufacturing shuts down. Those of us in commercial dry land farming don't have control over the light, and traditionally we haven't felt that we have any control over the moisture. Using the study (Pappendick/Ramig--more detail in post dated: Aug 19/2012)) that set me on this path, and seeing what is transpiring in our own operation, I have come to believe that we have significant influence on moisture. The above mentioned study, indicated how rainfall was used over a 10 year period: 1% went to deep penetration, 4% ran off the surface, 12% transpiration through the crop, and 83% evaporates off the soil surface. Our farming practices have a direct effect on three of these elements, and possibly all four. Cropping intensity addresses the 1%. Cropping intensity is more than annual cropping vs. fallow. It includes a cultivars root structure and it's individual moisture requirement. Mix and match these cultivars in a rotation to capture moisture before it escapes below the rooting zone. The quality, quantity, and position, of our crop residue effects the 4% and 83%. This means that our farming practices have an effect on 88% of the moisture our crops receive. This is powerful information. Our farming practices determine whether the moisture we receive is maximized for crop production, or frittered away. At the end of Dr. Pappendicks presentation in 1989, his concluding statement was: ---"You can't do much to change these numbers but it is best to keep the soil cool and the surface calm as possible". Since the 80's, things have changed. I would like to see this study redone using ULD technology and residue in place. We now have technology that will punch through a heavy mat of residue with very little surface disturbance. This same technology can be used with residue that stands as tall as the tractor cab. We now can successfully emerge a crop though conditions that allows us to keep the soil surface cool and the soil surface calm.
It's a given that the lower the rainfall, the harder it is to armor the ground with crop residue. Lower rainfall areas normally have progressively lighter soils, lower organic, silt and clay content and increasing sand content. The challenge to retain moisture and grow economically sustaining crops increases as one goes from a 15" to 7" rainfall regions HOW DOES ONE EVEN START IN THESE CONDITIONS? ---MY SUGGESTION IS AS FOLLOWS:
----Start by developing a new mind set on how to raise a crop. I have come around to believe that residue is everything. It is the basic building block for soil in dryland farming. If you see dirt, my conclusion is, you don't have enough residue. Build it, and protect it.
----Rethink what you raise for crops. Rethink fallow. Think beyond winter wheat!
----Will your soils store water? They probably do, at least for a short period of time, or you wouldn't be cropping the ground. An interesting exercise is to take a plank (suggest a 2x12x12) and place it firmly on a fallowed piece of ground when you start spring work. In the fall when you prepare to seed that fallow field, lift the plank and see if there is moisture, at the surface. If that small area shows dampness, that tells you that your soils have not wicked out, after a significant amount of time passage. To me, that is hope, and an opportunity. Residue will not replace a board; however, if the moisture had not wicked out the sides of that small impervious cap, it is an indicator that residue will help. I experienced this years ago. A chem fallow field with a dry fall, and sparse residue had moisture down 5", and under the board, there was moisture at the soil surface, so the question became: a--how to get residue to mimmic the board, and b--how do you seed the crop without losing that moisture (which was "thin").
----Take a piece of property and dedicate it to no-till and start building residue. You will likely need custom operators, so, look into that before you start. Successful no-till is management intensive and time sensitive. You have to get your mind around new ideas, and spray and drill operations have a narrower window for optimum response, over tillage.
----Build residue: a---quit all tillage and/or residue management practices. All interaction with residue degrades it (wheels, tracks, harrows, mowers, ect.). Because residue is fragile and easily destroyed you will need to do a ultra-low disturbance system (ULD) to have any hope of building and maintaining residue. b--most single disc, one pass drills qualify as ULD. If you have consistent soil conditions (same soil with no hard or soft areas, and an even spread of residue) the CrossSlot may not be the lowest disturbance one pass drill available. The CrossSlot is excellent in complex seeding environments. c---select cultivars that degrade slowly. Once a sufficient residue level is reached, protect it so you can start adding diversity in your cropping system.
----Add cover crops: I/We have no practical experience with this practice --only background information. We have made our first stab in the dark by seeding 70ac with a variety of cultivar mixes.
More than likely regular cropping will not develop significant residue even with all ULD tricks applied in the very low rainfall regions. This is where cover crops may play a role. a----raise a high biomass cultivar and terminate growth at max biomass prior to viable seed development. With this practice you are trading short term return for long term gain. This phase may take two cover crops raised back to back to develop sufficient residue. Cereal rye is reported to be an excellent builder of biomass. The caution here is to be sure that your seed lot is certified as a single cultivar. Apparently cereal rye is commonly marketed with as many as five undisclosed separate cultivars that mature differently. I think we are all familiar with what that means. b---once you get the soil surface protected then look at other factors of soil health, --structure and biological. Improved structure comes with eliminating tillage. I link high disturbance no-till to a reduced tillage practice.
----Rethink fallow. There are several studies done on the efficiency of fallow. These center around the rainfall received during the 13m fallow period and what is available for the crop following the 13m fallow period. The efficiencies ranged from ≈ 34% (in the PNW) to <20% (in the South). Stated another way, During the fallow period, 66% to >80% of the rainfall received is not available for crop production. It is lost to one of the other three factors,--deep penetration, runoff, evaporation.
The June 20th, 2015 addition of NO-TILL FARMER has an interview with an eastern Montana farmer. Very interesting! 14" rainfall area. He has ULD system, introduced cover crops and has increased his crop rotation, and removed fallow from his system with no loss of yield.
Earthfort Laboratory in Salem, OR is where we are going for testing of soil biological health. They have several tests, and programs to learn more about soil health and how to improve it. Their website is <www.oregonfoodweb.com>
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