Turnip Cover Crops
Dec. 5, 2011
By Orvin Bontrager
Planting turnips or other cool season cover crops is gaining in popularity in Nebraska, especially on seed corn production fields. Usually the seed at 2-5 pounds per acre is broadcast behind the machines that are chopping out or removing the male inbred. This allows the plants to become established while the field is still being watered. Taller and denser foliage corn inbreds have enough shading that the young turnip plants will grow very little, if at all, until the corn is harvested.
Cattle have been placed in most of the fields to graze the tops and even the turnip root that is largely exposed above the soil surface. Below is a field that has been heavily grazed and shows the top feeding on some of the roots.
The down side of the turnips are some cattle may be negatively effected by eating the tops, until they get used to eating the plants. The large roots can cause some choking and even death if not monitored very closely.
The turnips this fall have dried out the soil significantly because of lack of rain. Winter and spring moisture will need to refill the top 2-3 feet of soil or the 2012 summer crop will start off short of moisture.
Nov. 14, 2011
By Orvin Bontrager
Corn harvest is rapidly winding down in central Nebraska. An extensive dry period since Sept 1 has allowed the crops to be harvested with little soil compaction.
Soybean yields were good but not great. The shorter season mid group II’s yielded higher than the longer season late group II to early group III’s. Soybeans dried down very rapidly. It was very difficult to harvest in the 12-13% seed moisture range. Many dropped to 8% moisture from the warm dry winds. 3-4 bu/ac yield losses result from the very dry beans.
Whole field averages of 70 bu per acre were fairly common, but many had higher yield expectations based on the number of pods. Some soybeans shriveled back in the pods and the 3 bean pods turned to 2 bean pods. Post emerge fungicides seemed to be hit and miss on payback.
Corn dried much better than expected. Harvest got off to a late start, but warm dry winds dried the corn fairly well. Plant health was excellent. Many fields had a post tassel fungicide applied. With little rainfall in Sept and Oct, corn leaves stayed very green for the most part. Late stalk strength was good and stalk rots were minimal where the crop was managed properly with late irrigation water and fungicide applications.
Overall corn yields are off about 10 bu per acre from last year. Pretassel greensnap hurt many hybrids, some severely. Areas that had extensive greensnap in 2010 had better corn this year. The very hot nights stressed the pollinating crop and contributed to poorer yields. Some hybrids took the stress better than others. Not giving up on the fields that had broken plants by proper water and fungicide application still produced respectable yields. Seed corn inbreds and white corn hybrids were hurt the most from pre-tassel breakage.
Sept. 28, 2011
By Orvin Bontrager
Central Nebraska is ending up dry now with harvest starting on the mid group II soybeans. Early yield reports are excellent with whole field averages in the mid 70’s bu/ac including the non irrigated corners. Unless one had earlier hail damage, the soybeans appear to be having a very good year.
Some ear rot is showing up on corn hybrids that have a softer kernel and tighter husk. This is a quality and yield concern. If deterioration continues before the grain is harvested, more of the effected kernels will be thrown over by the combine. Storage of the crop will be less than ideal. Pictured are some ears observed several days ago with kernel rotting from possibly Fusarium pathogens. The kernels were still not quite at the black layer stage or physiologically mature yet.
As a whole the corn is finishing with excellent plant health. Many fields were treated post tassel with a fungicide. From late August to the present, the humidity dropped and we have experienced cool nights and sunny days. This has put less stress on the corn plants to finish well.
Goss’s wilt is a predominant disease issue that will have to be addressed next year again. Somewhat susceptible hybrids showed symptoms even on rotated soybean ground. One will need to watch corn hybrid selection very carefully on continuous corn fields for 2012.
Warmer temperatures are needed to help finish the corn and aid in some field dry down before harvesting. We are running significantly behind the early harvest of 2010.
Aug. 31, 2011
BY ORVIN BONTRAGER
After a hot, very humid growing season over much of July and Aug, cooler nights are finally being experience lately. This will help greatly at finishing the corn crop with good test weights.
We are on the last days of irrigating, if no substantial rainfall occurs. It is important to finish strong and to not allow the crop to run short of water. Corn is mainly in the ¼ to ½ starch line stage of development. Corn at this stage will still use 2.0 –3.5 inches of water. If the water isn’t readily available in the soil profile, irrigation is needed.
In much of the area, post tassel fungicides were applied to the corn crop. Results look positive at this time. Because of past experience, a non mite flaring insecticide was applied with the fungicide to control and hold down the later developing bird cherry oat aphids. Fields that didn’t have that application in some cases developed high levels of the aphids on the lower to middle parts of the plant. Treatment guidelines have not been researched for these aphids, but past experience has shown that they tend to cause poorer corn stalk quality in the fall where heavily infested. This has been a recent phenomenon in the recent 4-5 years.
Where the corn was watered correctly and fungicides were applied, pollination issues are not being reported as much. Pretassel greensnap that occurred during a high wind event on the night of July 10 will limit production in areas of some fields on hybrids that were vulnerable. Some seed corn fields were heavily damaged.
Soybeans look very good at this point. Pods are full on many of the early May planted group 2.5 to 3.0 varieties. Yellowing is occurring on the early maturing varieties. A full profile now on silt loam soils will finish most of the earlier planted soybeans now. Limited soybean aphid and bean leaf beetle treatments occurred on the early planted fields. Some recent treatment has taken place on the later May to June planted fields.
As always, finishing strong is important to maintain good plant health on the corn and fill the last top pods on the soybeans.
April 27, 2011
By Orvin Bontrager, Servi-Tech Director of Education
Cover crops are being promoted for nutrient cycling and increasing crop yields on no-till fields in Nebraska.
Several strips were planted the end of August 2010 on non-irrigated wheat stubble in Hamilton County in south-central Nebraska. A mixture of radishes, turnips, winter peas, and oats was in the planting.
Pictured below is the cover crop on the right in early Nov 2010. Only 1-1.5 inches of moisture was received after planting in the fall. The check is on the left. Weeds were treated in early Aug prior to planting the cover crop. The check strips had volunteer wheat controlled again in Sept 2010. The strips are replicated 5 times.
The same strip is shown this spring. The cover crop winter killed, but some volunteer wheat remains. It has been scheduled to be treated but inclement weather has prevented herbicide application. Anhydrous ammonia was knifed into the soil on both strips.
Soil moisture samples show that significantly drier subsoil exists in the cover crop strips. These were taken several weeks ago prior to 3.5 inches of rain that have been received in the past 10 days.
The data shows a combined 1.59 inches less water was present in the cover crop strips than in the weed controlled wheat stubble strips.
The same samples show 112 total pounds of nitrate nitrogen available in the top 3 feet of the wheat stubble check and 22 pounds available under the cover crop strips. However some of the nitrogen taken up by the cover crop will become available to the corn crop this summer as the cover crop residue breaks down.
A non irrigated corn crop will be planted and monitored this spring. Yields will be obtained for comparisons this fall.
April 19, 2011
By Orvin Bontrager
Corn planting has started in south-central Nebraska. Soil temperatures are still plenty cold. My recent readings are 48-50 degrees F at 4 inch depth on continuous corn ridges. The near term forecast won’t allow them to warm up much. As I write this over 1 inch of rain has been received and planters won’t be moving for several days now.
Burndown herbicide treatments for winter annual weeds are progressing rapidly. The major problem weeds are various mustard species and several annual brome species. Shepardspurse is one of the more difficult to control annual weed.
Fields that have been historically managed for winter weed control have much less pressure than fields that have been ignored. Now with rain and wind delays, the untreated fields will have the winter weeds grow and progress rapidly.
Even with wetter conditions, research has shown that the early weeds reduce both corn and soybean yields by competing for soil moisture and nutrients. A week of warm, dry weather will allow the weeds to dry out ridges and planting areas rapidly. The crop is then stunted in those weed infested spots.
2,4-D is a valuable addition to any burndown program on fields going to soybeans. It aids greatly in giant ragweed, smartweed, lambsquarter and horseweed/marestail control. If it isn’t on now, the growers will have to hurry to get it applied so soybeans can be planted by the end of April. 2,4-D needs to be on at least 7 days prior to soybean planting; use only the ester formulations of 2,4-D.
March 7, 2011
By Orvin Bontrager
This is a continuation of the discussion about the changes in soil fertility over time based on various farming practices; particularly certified organic production verses farming practices that utilize fertilizers and pesticides.
The soil results I am presenting are composited soil samples obtained in the past 20-25 years, depending on the field represented. Each sample is a composite of 10-20 acres at the time of soil sampling. The same sample depth of 9-10 inches was performed and the soils were tested at the same soil testing laboratory.
Very little change has occurred in the organic matter results. This would give a good indication of the overall soil fertility of the fields. The first three years of the sampling period for each field were averaged and compared with the last three years that soil samples have been obtained.
The following table shows two certified organic fields compared with four conventional fields I have checked for the past 20-25 years.
The four conventional fields were chosen because their soil types are similar to the organic fields. They were a few of the fields on which I have the longest records available. The long term averages of the organic fields were 2.57% organic matter 20 years ago verses 2.56% now. The averages of the four selected conventional fields were 2.48% OM 20-25 years ago verses 2.39% now. Without the benefit of true replicated trials, I would consider these differences in OM to be non-significant.
I attended a presentation by A. E. “Johnny” Johnston, Rothamsted Research, at the AICC conference near Birmingham, UK in January. His long term research indicates that soil OM changes very slowly. It will reach equilibrium in time and we can’t affect or change it significantly.
Continued yearly monitoring of crop production fields is important to document how the soil organic matter is changing from the various cropping practices. Long term averages are important to monitor verses sporadic sampling that may show trends that are not truly occurring.
March 1, 2011
By Orvin BontragerServi-Tech, Inc.
I finished reading the book, Dirt: the Erosion of Civilizations, in the past week by David R. Montgomery, professor earth and space science at University of Washington. Although I personally believe there are additional factors in causing civilizations to collapse, Mr. Montgomery certainly makes valid points on the importance of conserving our soil resources to adequately feed our growing population.
He is critical of the modern “American industrial farming” methods. I am not going to debate whether we should be promoting or subsidizing more organic production instead of the more conventional agriculture. I believe the market system will sort out the desired methods of production.
Much evidence is cited to promote his thesis that more organic production with more “labor-intensive systems” will sustain our soil longer without the high cost of fertilizer and pesticide inputs. Undoubtedly returning more manure back into the fields will be beneficial. The uneven distribution of large feedlots across the High Plains and western Corn Belt doesn’t allow manure to be placed economically back on many fields now.
My experience in the past 26 years in south-central Nebraska has shown a plateauing of organic matters in the soil tests. This is on both a long term certified organic farm I have been checking since 1989 as well as the surrounding conventional produced land with the same silt loam soil types. The soil tests are done yearly on all the fields. It is very important to compare some soil sample depths and even same soil labs for long term results.
I haven’t seen an increase of organic matter on the organic fields with an alfalfa-corn-soybean-wheat-alfalfa rotation compared to the conventionally farmed corn-soybean or continuous corn rotation in the area. The phosphorous levels have increased somewhat more on the organic fields due to 2-3 tons per acre composted manure applications on selected areas of the farm each year. The organic matters have stabilized in the 2.5-3% range on a 9-10 inch soil sample depth on both organic and conventional fields.
The organic farm has to be tilled for weed control. The other surrounding fields are more modified ridge till to even no till. Less organic matter destroying tillage is done on the corn-soybean rotations than on the organically farmed ground.
These are my observations of walking and routinely checking fields on a weekly basis as well as yearly composted soil samples. They are not replicated small plots or strips that most published research projects entail.
I am going to discuss this issue more next time.