Location: Soil Management Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Identify and develop new and alternative crops and cropping strategies for the northern U.S. • Sub-objective 1-1. Identify best adapted species/genotypes of new, alternative, and traditional crops for biofuels and bioproducts production in northern climates. • Sub-objective 1-2. Develop innovative, and improve existing strategies for managing new, alternative, and traditional crops. • Sub-objective 1-3. Determine environmental limitations on growth, development, and seed oil and nutritional quality of new, alternative, and traditional crops. Objective 2: Develop new strategies and decision aids to improve and increase the efficiency of weed management. • Sub-objective 2-1. Develop biological models of important invasive and prominent weeds, stressing critical life history events. • Sub-objective 2-2. Develop and improve weed management models. • Sub-objective 2-3. Explore feasibilities of entirely new strategies of managing weeds, focusing on increasing research on biologically-based integrated weed management.
1b. Approach (from AD-416):
Two mutually supporting approaches will be taken to meet our objectives. The first involves a series of field studies to identify new (e.g. cuphea, pennycress, and bifora) and alternative crop genotypes (e.g. camelina and calendula), develop practices to manage them, and use these crops along with traditional crops to develop alternative strategies (double- and relay-cropping) to add innovative economic and environmental benefits. Additionally, controlled-environment and field experiments will be conducted to determine environmental limitations (e.g. water and soil and air temperature) to growth of new and alternative crops. The second approach involves the integration of field and controlled-environment experiments of weed growth and development, innovative weed control methods, and computer modeling to develop decision support aids to efficiently and effectively manage weeds in cropping systems that include new and alternative, as well as traditional crops. Together the outcomes of this research will provide clientele with new knowledge, crops, and management tools to increase cropping efficiency and diversity in northern climates.
3. Progress Report:
We worked on two primary objectives: 1) identify new and alternative crops and develop cropping strategies to integrate these crops with traditional crops while adding environmental and economic benefits; and 2) integrate weed growth and development data, innovative weed control methods, and computer modeling to develop decision support aids to efficiently and effectively manage weeds in cropping systems for both new and traditional crops. For our first objective, we identified forage sorghum as an excellent annual biomass/forage crop that can be double- and relay-cropped with winter camelina and potentially, pennycress. These latter crops are oilseed species being developed for biofuel/bioproduct feedstock. Although sorghum is considered a mid and southern US crop, we demonstrated yields of 16 Mg ha-1 when relay-cropped and 26 Mg ha-1 when mono-cropped, which rivals corn for this region. Our research discovered the cardinal temperatures (base, optimum, and maximum) for calendula seed germination, which will help farmers growing calendula (as an oilseed) to target optimum planting date based on soil temperature. Research revealed that camelina can be planted deeper than previously recommended, which allows better seed-to-soil contact and can improve emergence and stand establishment. Initiated study to determine productivity of several spring and winter Brassica-related varieties, already revealed that "Joelle" camelina has superior winter-hardiness compared to canola and oilseed rape. Research success helped secure 2012-13 funding to study beneficial relationships of rotating diverse new/alternative oilseeds on pollinator (e.g., bees) abundance and health. Progress toward our second research objective included field demonstration that camelina is tolerant to ethalfluralin and pendimethalin used as pre-emergence herbicides but that clopyralid used as a post-emergence herbicide caused floral sterility despite not effecting vegetative growth. Additional field studies identified bromoxynil as an acceptable post-emergence herbicide for cuphea. Continued greenhouse and field testing to identify and verify tolerances of calendula, echium, and cuphea to additional pre- and post-emergence herbicides. Results will be used for recommendations and grower guides for producing these new oilseed crops. Our team researched new organic weed control tactics. The first method uses the grit of various plant residues, such as corn cobs, or organic-approved fertilizers, propelled by compressed air to abrade and kill weed seedlings within crop rows. Collaborators constructed a prototype multi-row, tractor-pulled applicator, which is being field tested. A video can be viewed at: http://www.ars.usda.gov/Services/docs.htm?docid=22766. A second method of organic-compatible weed control is rolling/crimping of winter rye at anthesis, which is followed immediately by planting short-season soybean varieties. Although this system lowers soybean yield up to 30%, it also achieves >95% weed control. Because organic soybean is valued at nearly twice that of conventional soybean, the method exceeds conventional soybean in terms of net returns to growers.
1. Optimizing production practices for new oilseed crops. Information for optimizing production of the new oilseed crops, camelina and calendula, is lacking. ARS researchers at Morris, Minnesota, demonstrated that camelina and calendula are not heavy nitrogen users and can be fertilized at lower rates than most common commodity crops. Camelina was found to have a higher nitrogen-use efficiency than its close relative, canola. Farmers producing these crops can save money by fertilizing with less nitrogen, which also benefits the environment. Researchers also showed that from late April to early May is the best time to plant calendula in the northern Corn Belt, and that its length of maturity (from planting to harvest) is intermediate to spring wheat and soybean, making it a good rotational crop for this region. Seed yields as high as 2100 lbs/acre at a seed oil content of 20% were achieved with a new hybrid developed in the Netherlands, which yielded higher than a slightly older, standard open-pollinated variety named Carola. Research also identified two new post-emergence applied herbicides (imazamethabenz and desmedipham plus phenmedipham) tolerated by calendula, which gives farmers more options now for controlling weeds in calendula.
2. Double-cropping with winter camelina in the northern U.S. The US is currently pushing for the development of renewable energy, including biofuels, to replace petroleum. However, there is concern over the economic and social acceptability of using food crops for fuel or using land for growing dedicated biofuel crops that could otherwise be used for producing food. ARS researchers at Morris, Minnesota, demonstrated that camelina grown as a winter annual crop, which can serve as dedicated biofuel feedstock, can be harvested early enough the following summer to allow production of a short-season food or feed crop such as soybean, sunflower, and millet. Thus, both a biofuel and food/feed crop can be produced on the same land in a single season. Although double-cropping is more expensive than producing a single crop, research showed that a camelina-soybean double crop sequence was both feasible and economically attractive. In one year of the two-year study, the camelina-soybean sequence resulted in net earnings of $70 to $142/acre more than if a single crop of soybean was grown. Moreover, there was no sacrifice in seed quality of double-cropped soybean and only a small affect on double-cropped sunflower seed quality over the two-year study. This newly developed cropping strategy allows farmers to produce both biofuel and food or feed on the same land in a single growing season; winter camelina can serve as a "cash" cover crop, which farmers in the Midwest are seeking.
3. Predicting ripgut brome emergence using hydrothermal-time model. Ripgut brome (aka great brome) is a weedy grass of Mediterranean-type climatic regions, such as Spain and California. It can be a problem for livestock grazing in rangelands and is a serious competitor with actively growing crops like winter barley and wheat. By knowing when ripgut brome seedlings emerge in autumn relative to when winter cereals are planted, farmers can time seedbed preparation and planting of their crops to minimize ripgut brome populations. ARS researcher at Morris, Minnesota, collaborated with scientists from the University of Lleida in Spain to develop a hydrothermal time model to simulate ripgut brome seedling emergence. Seedling emergence data collected from select fields in northeastern Spain and simulated soil temperature and moisture data (from software created by ARS-Morris) for these fields were used to develop the mathematical model. The accuracy of the model was tested by comparing predictions of emergence with observations made in other fields in northeastern Spain and an entirely independent field in southern Spain. Predictions compared well with observations for all sites indicating that the model can be used to estimate emergence at any location (including California) where ripgut brome causes problems. Use of this model by ag professionals will assist farmers in making wise decisions regarding seedbed preparation and planting dates wherever high ripgut brome populations exist.
4. Site-specific models of seedling emergence. Site-specific models of seedling emergence can be very accurate, but regional models often lose precision. A group of weed biologists led by ARS scientists from Morris, MN, examined this issue for the summer annual weed, giant ragweed, from across the Midwest (Ohio to Nebraska). Hydrothermal time during spring explained much of the variation in the timing and extent of seedling emergence across sites, but significant levels of variation still existed. The team found that low overwinter soil temperatures, which relieve seed dormancy, were critical additions to seedling emergence models that increased modeling efficiencies and accuracies. The specific model for giant ragweed will be valuable to crop advisors and the agrichemical industry who must deal with extensive herbicide-resistant populations of giant ragweed, and the general approach to modeling will be useful to other weed scientists.
5. Weed control in organic cropping system. Organic soybean often is at about twice the price of conventional soybean. However, yields of organic soybean typically are low, often because of severe weed competition. Organic growers need organically-compatible techniques that reduce weed competition with crops. Researchers from ARS at Morris, Minnesota, examined the effects of rolled/crimped winter rye on weed pressure in short-season soybean in Minnesota. Rolled/crimped rye reduced weed pressure by >95% in soybean and eliminated the need for hand-weeding, but it also reduced soybean yield by up to 30%. Lower soybean yields did not negate the practice because of the high net returns of organic soybean and the cost-savings in terms of weed control still were appreciably greater than the net returns from conventional soybean. This information is of value to organic growers and their crop advisors.
6. Post-emergence weed control with air-propelled abrasive grit. Organic row crops need additional techniques of effective weed control. Selective post-emergence control of weeds with air-propelled abrasive grit has been successful in corn, but selectivity in other crops is not known. Researchers at Morris, Minnesota, tested abrasive grit selectivity in soybean in both greenhouse and field environments. Soybean was found to be insensitive to grit applications at all tested crop growth stages except the fully open cotyledon stage. At this stage, grit applications could reduce crop stand in field settings and unifoliate leaf area in greenhouse experiments, but soybean yield never was lowered. Consequently, abrasive grit can be applied at least twice from the time of soybean emergence to the time of the second trifoliate leaf stage without lowering soybean yield, but applications at the cotyledon stage probably should be avoided. This information is of value to organic growers and their crop advisors.Johnson, J.M., Gesch, R.W. 2013. Calendula and camelina response to nitrogen fertility. Industrial Crops and Products. 43:684-691.