Kelly Cooper, NDSU Carrington Research Extension Center
The Conservation Cropping Systems Project (CCSP) is located on a 130-acre tract of farm land two miles south of Forman, ND along Highway 32. A 14 member Board of Directors composed of local producers in northeastern South Dakota and southeastern North Dakota advises the CCSP staff. Diverse crops are grown in 15 rotations that range from one to six years under no-till, mechanical strip till, bio- strip-till, shank and disk drill cropping systems. A total of 172 60×220 foot plots plus several irregular shaped “bulk area” plots ranging from 1/10 acre to 8 acres are used for production and demonstrations. Rotations are demonstrated to look at their effect on water and wind erosion, soil tilth, soil moisture retention, organic matter changes, and profitability. Each crop within a rotation is grown every year and replicated three times. Other practices and demonstrations done currently or in the past include variety trials, livestock waste applications, carbon sequestration studies, weed control experiments, livestock grazing, saline cover crop and saline alfalfa trials, biological strip till, radish rooting depth, and equipment demos to name a few.
By the time it was fit to start planting corn, it was time to be finishing. When we were planting wheat, there was some corn planted in the area. Some of it did ok, some needed to be replanted. Planting corn in bad conditions is just the norm in North Dakota it seems. Whether it is mid-April or mid-May. The frost apparently was not out until June this year. Board member shared my experience on CCSP farm. Wheat stubble was the first ground we could get into. The stubble caught what little snow there was and limited frost depth. Soybean ground had deeper frost. Our loam and clay loam soil took on the consistence of angel food cake. I did not get stuck but left rather deep depressions. “Waffle Tracking” was the name given by one board member. Where these tracks were made, the corn looked tough the whole year. Compaction, nitrogen loss, hard to say exactly what, but it was not good for yields. The higher, well drained plots obviously did better. The N rotation, where corn follows alfalfa, was the clear winner which is by past experience very predictable on a wet year. What also has become predictable is flax as a previous crop is always near the top. This makes me wonder if flax would be a good choice as a cover crop to fly on soybeans mid to late season.
Our Strip till/Variety trial was done in the large bulk area this year. With the late spring, I thought it would be a good opportunity to look at 85-90 day corn planted late. Unfortunately this plot was negatively affected by the wet June. I should note that large areas just to the SW of the CCSP farm intended to be planted to beans ended up being prevent plant. Overall, the yields were low on all varieties. The multiple wet spots that developed in the plot area rendered the data unreliable for the most part. It is interesting to note we had a very low advantage to strip till for 2014. At one point, near the 2 foot tall stage, the strip till looked quite a bit better.
The bio-strip was unremarkable this year. Bio-strip, also called precision cover cropping, is where radish is planted in rows after winter wheat harvest, where the following year’s corn will be planted. In between the radish rows, peas are planted. The theory is the radish will scavenge nutrients and bring them close to where the corn plant will be next year. Corn is reportedly very compatible with radish, and does well following Brassicas in general. The corn roots will also follow the radish roots allowing for faster, deeper rooting. The peas planted in-between will add nitrogen and carbon to the system. Last year this rotation did very well. I should note this is a very low disturbance rotation, with no mechanical strip till. The cover crop growth was marginal in the fall of 2013, but adequate. The drawback this year could be the slower warm up as compared to the alfalfa, flax, and strip tilled ground, but the strip till trial did not support that theory.
I do have a new plan for the bio strip that I have been thinking about for a while. This fall, on the first bio strip plot, I forgot to turn off the fertilizer pump on the 7200 planter. After about 50 feet I noticed fluid blowing out and realized my mistake. The results were a very vigorous crop of brassicas where they got a rather large dose of N. The peas were unaffected. We also had nice moisture for growth as well. The winter wheat stubble typically has a very wide carbon to nitrogen ratio and this year very little residual soil N. I am thinking about giving the radish/brassica mixture a large shot of nitrogen, to not only enhance their growth but to hopefully capture more carbon. This extra nitrogen may get partially immobilized but should be of benefit to the following corn crop. If we can run this plan for several years I would hope to see a faster increase in soil organic matter. Higher organic matter would then lead to a reduction in applied nitrogen needs. The real question I have is how much nitrogen will be available to the immediate corn crop. One of many unknowns is at what level does the soil organic matter need to be at before an equilibrium is reached. Or, there may not be a level that is steady, but a range of fluctuation. Although no one talks about it very much, the amount of nitrogen released by the soil that is available for crop growth varies considerably from one year to the next. I have seen replicated research plots where 200 bushel corn was grown on 14 lbs of applied nitrogen, without manure. This is a somewhat rare event, but it does happen.