H. Mark Hanna

Drought impact on crop production and the soil environment: 2012 experiences from Iowa

Enormous challenges were presented by the 2012 drought. Poor water availability and high temperatures resulted in significant stress during critical phases of corn (Zea mays L.) and soybean (Glycine max L.) development. These stress factors lead to management challenges with insects, diseases, and reduced nutrient availability and uptake by plants. The drought triggered soil changes, particularly in conventional tillage systems, such as increased fracturing, crusting, and deterioration of soil structure and aggregation. All this reinforced the need for soil conservation planning, especially its necessary role in buffering against unpredictable conditions and the impacts of dry and wet events on production and soil quality. In 2011, the USDAs National Drought Mitigation Center reported that 43% of Iowa experienced moderate-drought conditions and nearly 10% experienced severe-drought conditions. In 2012, 100% of Iowa experienced severe-drought conditions, while 65% experienced extreme-drought conditions by October. This article addresses several effects of drought on soil and crop production and lessons learned that will help develop appropriate drought mitigation strategies for future soil and crop management practices. The 2012 drought created unfavorable soil conditions for plant development and growth and changes in soil structure in many areas in the Midwest. These changes in soil structure included fracturing…

Tillage Implement Operational Effects on Residue Cover

Crop residue cover protects soil from erosion caused by raindrop impact and runoff. Fall and spring season factorial field experiments indicated that operator-controlled adjustments of tool configuration, depth, and under certain conditions speed affected corn residue cover buried by a tandem disk harrow and chisel plow and soybean residue cover buried by a knife-type fertilizer applicator.

Midwest vision for sustainable fuel production.

This article charts the progress of CenUSA Bioenergy, a USDA-NIFA-AFRI coordinated agricultural project focused on the North Central region of the US. CenUSA’s vision is to develop a regional system for producing fuels and other products from perennial grass crops grown on marginally productive land or land that is otherwise unsuitable for annual cropping. This article focuses on contributions CenUSA has made to nine primary systems needed to make this vision a reality: feedstock improvement; feedstock production on marginal land; feedstock logistics; modeling system performance; feedstock conversion into biofuels and other products; marketing; health and safety; education, and outreach. The final section, Future Perspectives, sets forth a roadmap of additional research, technology development and education required to realize commercialization.

CULTIVATOR DESIGN FOR INTERROW WEED CONTROL IN NO-TILL CORN

More than 95% of Iowa row crop acres are treated with herbicides. Such extensive use is an environmental concern. Banding of herbicides over the crop row, along with mechanical cultivation to control interrow weeds, has been proposed as a way to reduce herbicide use. Though cultivation is used on 74% of Iowa corn (Zea mays L.) land, herbicides are applied in a band on only 17% of the corn acres. This indicates that cultivation is not relied upon for interrow weed control. The risk that weather conditions will hinder completion of mechanical cultivation seems to discourage the use of herbicide banding. Higher speed cultivation could improve the odds of timely completion of needed cultivation. An experiment was conducted on a Clarion loam soil near Boone, Iowa in 1993 through 1996 to determine the effect of cultivator design and speed, when combined with the banding of chemicals, to control weeds. Three cultivator styles, two bands [19 cm (7.5 in.) and 38 cm (15 in.)], and two speeds were tested. A single cultivation management strategy was used. Data were taken in a no-till continuous corn rotation on 76-cm (30-in.) row spacings. Faster speed did not impede weed control or yield. In two years, the corn yield was greater and weed cover was reduced in plots cultivated at 11.2 km/h (7.0 mph) than in plots cultivated at 6.4 km/h (4.0 mph). Weed populations were greater in the 19-cm (7.5-in.) band than in the 38-cm (15-in.) band three of four years. In three of four years, leaf heights and yields were also significantly less for herbicide applied in a 19-cm (7.5-in.) band than in a 38-cm (15-in.) band. There was no difference between yield in a broadcast treatment and treatments which used a wide band of herbicide and a cultivator with disc hillers. In two years, the sweep and smith fin (a vee-shaped flat sweep with low rake angle) cultivator treatments resulted in less weed cover than the point-and-share treatment. In one year, the sweep and smith fin cultivator treatments had greater yield than the point-and-share treatment. Groundcover among cultivators showed few differences.

FIELD EVALUATION OF ANHYDROUS AMMONIA MANIFOLD PERFORMANCE

Experiments conducted between August 1999 and April 2002 evaluated anhydrous ammonia manifold distribution during field application at 84- and 168-kg N/ha (75- and 150-lb N/acre) application rates. Multiple manifolds including the conventional (Continental NH3 Model 3497, Dallas, Tex.), Vertical-Dam (Continental NH3 Dallas, Tex.), RotaflowTM(H.I. Fraser Pty Ltd, Sydney, Australia), Equa-flowTM(PGI International, Houston, Tex.), FD-1200 prototype (CDS John Blue Co., Huntsville, Ala.), and the Impellicone prototype manifold were tested. Temperature and pressure data were collected along the flow path. Results showed high distribution variation by the conventional manifold at both application rates, with average coefficient of variation (CV) values in excess of 16%. At the 84-kg N/ha (75-lb N/acre) rate, all other manifolds tested had significantly lower application variation (. = 0.05). At the 168-kg N/ha (150-lb N/acre) rate, the conventional manifold grouped statistically with the Vertical-Dam with a corn ring and the FD-1200 prototype, producing CV values between 9.5% and 16.2%. All other manifolds had significantly lower application variation. The Impellicone, Rotaflow., and Equa-flow., manifolds performed with the lowest measured variation at both rates, yielding best performance at the 168-kg N/ha (150-lb N/acre) rate with CV in the 6% range. Analysis of recorded temperature and pressure data indicate that NH3 flowing through the system very closely follows the saturation line and acts as a saturated mixture. Predictions of NH3 quality based on calculations of an ideal adiabatic mixture are supported by this result. Investigation for correlation between CV, air temperature, and percent of volume in the vapor phase of NH3 resulted in only a visual trend that may suggest a reduction in CV with lower percent of volume in the vapor phase. Results suggest that replacement of a conventional manifold with a Vertical-Dam manifold or any of the other manifolds tested could reduce application variation between 7.0% and 16.5% at 84 kg N/ha (75 lb N/acre) and 1.0% and 10.2% at 168 kg N/ha (150 lb N/acre). This change could reduce application rate by eliminating the need for over-application to compensate for variations.

Effects of Nozzle Type and Carrier Application on the Control of Leaf Spot Diseases of Soybean

Midwestern soybean growers seek information on effective application of foliar fungicides that do not translocate throughout the plant. Field application treatments included using a two-orifice nozzle tip producing fine droplets at 187 l/ha (20 gal/ac) and 112 l/ha (12 gal/ac) and a single-orifice nozzle tip producing a coarse droplet size more typical of herbicide applications at 168 l/ha (18 gal/ac). In addition an air-assisted sprayer was used at one of the two sites of the trials. Measurements included droplet size, droplet coverage, and foliar disease severity in the top, middle, and lower parts of the plant canopy, and soybean yield. Droplet size for application treatments generally followed expected manufacturer specifications. Percentage area covered and drops/cm2 were not statistically different among application treatments except at top of the plant canopy at one site. Percentage area covered and drops/cm2 were statistically greater at the top of the canopy (17 - 18% coverage) than at the middle or bottom (1 – 8% coverage) at both sites. Foliar disease pressure was light so that yield or disease severity was unaffected by application method or as compared to a check area without application.

An Interactive Spray Drift Simulator

The off target movement of pesticides, known as spray drift, results in a reduction in application rates, damage to non-target organisms, and environmental concerns. Much of this drift can be eliminated if its prevalence is understood and best management practices are implemented. Drift prediction software has been developed to serve as a management tool in determining the effects of applying pesticides under certain operating conditions. To further increase the usefulness and instructiveness of such programs, a program was developed which links spray drift prediction software (DRIFTSIM) with a GPS simulator to obtain a two dimensional representation of drift for simulated ground based spraying event. The program was evaluated using a variety of operating conditions to determine their respective effects on drift deposition levels. Results from the simulations show the importance of choosing the largest sufficient nozzle size, operating under low wind speeds, and spraying at the lowest possible boom height. Analysis of multi-swath simulations showed patterns of increased and reduced application rates due to spray drift.

Harvesting, Storing, and Post-Harvest Management of Soybeans

Publisher Summary This chapter describes the systems and procedures for harvesting, drying, handling, and storing Soybeans (SB). These operations are interdependent and all must be carried out correctly so that the quantity and quality of the soybeans are as high as is practicable when the crop is marketed and processed. The chapter presents some recommendations for harvesting, drying, handling, and storing soybeans, along with some history, recent developments, and trends for the future. The most important property of soybeans associated with their harvesting, drying, handling, and storing is moisture content. Soybean moisture content is defined assuming soybeans consist of two components: water and dry matter. Wet-basis moisture contents are used in the grain trade and in most other instances. Dry-basis moisture contents are sometimes used in research, especially related to the drying process. The chapter highlights that all moisture contents stated in the chapter are on wet basis.

Field Application Uniformity of Impellicone and Pulse-Width-Modulated Anhydrous Ammonia Manifolds

With the consistently increasing cost and widespread use of anhydrous ammonia (NH3), producers are looking for ways to reduce variability in applicator equipment. One way to improve uniformity in NH3 applicators is the use of a better distribution manifold. Impellicone and pulse-width-modulated (PWM) manifolds are newer design alternatives to a Vertical-Dam manifold. Uniformity measurements during field application were made comparing Vertical-Dam manifolds with several Impellicone manifold designs and also a pulse-width-modulated (PWM) valve design as these manifolds were refined for commercial production. Application rates ranged from 23.7 to 224 kg N/ha (21.2 to 200 lb N/acre) depending on experiment with many applications near 84 kg N/ha (75 lb N/acre; “low” rate) and 168 kg N/ha (150 lb N/acre; “high” rate) during Impellicone tests. Modified Impellicone and PWM manifolds both had better uniformity at a 99% confidence level (as measured by lower coefficients of variation (CVs)) than did Vertical-Dam manifolds tested during the same field conditions. Modified Impellicone manifolds had average coefficients of variation (CVs) 9 and 6 percentage points lower, than the Vertical-Dam manifold at the low rate and high application rates, respectively. The PWM manifold CV was 3 percentage points lower than the Vertical-Dam at application rates of 95 kg N/ha (85 lb N/acre), but 6 and 13 percentage points lower than the Vertical-Dam manifold at application rates of 179 and 22 kg N/ha (160 and 20 lb N/acre, respectively).

Chapter 6 – Grain Harvesting Machinery

Abstract This chapter covers the components of grain harvesting machines, including crop gathering systems, conveyors, thresher, separator (often integrated) to separate threshed grain from stems and stalks, cleaning shoe to remove small/light material, storage bin to hold clean grain until it is unloaded onto a transport vehicle to be moved from the field, and material handling equipment (conveyors) required to move crop material throughout the machines.