Roger W. Elmore

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…

Alternate-furrow irrigation for soybean production

Abstract Alternate-furrow irrigation reduces water application without affecting yield and thereby leads to more efficient water use. A 2 year (1988–1989) field study was conducted to compare alternate-furrow irrigation to conventional every-furrow irrigation with soybeans [ Glycine max (L.) Merr.] at the South Central Research and Extension Center near Clay Center, Nebraska on a Hastings silt loam soil (fine, montmorillonitic, mesic Udic Argiustol). Conventional 0.76-m irrigation (every furrow) and wide 1.52-m irrigation (alternate furrow) were compared in relation to soybean yield, water use efficiency, soil water change, and water advance down the furrow. The soybean cultivar Resnik (indeterminate, group III) in a twinrow planting system was used. The two furrow irrigation treatments were evaluated in a randomized complete block with six blocks in each year. Yields were similar in the two furrow irrigation treatments although less water (46% less gross and 29% less net) was applied to the alternate than to the every-furrow irrigation treatment. Total water use efficiency (TWUE) was 6.12 and 5.52 kg·ha −1 ·mm −1 for the alternate and every-furrow irrigation, respectively. Net irrigation water use efficiency (NIWUE) for the alternate and every-furrow treatments were 57 and 36 kg·ha −1 ·mm −1 , respectively, across the 2 years. Runoff was less in the alternate-furrow irrigation treatment. There was no effect of furrow irrigation spacing on soil water change in the 1.52 m soil profile during the irrigation season. Alternate-furrow irrigation produced the same yield as every-furrow irrigation with less water input leading to water conservation.

On-farm experiment designs and implications for locating research sites

Research plots that are large enough to accommodate regular farm machinery are thought to contain too much field variation to allow reliable interpretation of experimental results. This study was conducted to determine whether experimental error was controlled on a wide variety of agricultural field trials that used plots larger than normally used by researchers. The investigation included trials conducted on an experiment station and trials conducted on actual commercial farms. The planning and management of the experiments ranged from those completely conducted by university researchers to those completely done by farmers. The level of experimental error in all the trials was well within the limits normally accepted by researchers in agronomy. Plots ranging in length from 125 to 1200 feet and as wide as one or two passes of standard farm machinery gave experimental results that were statistically sound. Statistical requirements for randomization and replication were all met. The ability to use large plots and farmer participation enhances the testing of new technology on farms. This leads to new opportunities to test crop production factors in a systems setting under actual farm conditions. The statistical reliability of the on-farm designs analyzed in this study should increase cooperation among researchers, extension workers, and farmers in research activities.

Growth stage scheduling criteria for sprinkler-irrigated soybeans

SummarySoybean [Glycine max (L.) Merr.] producers in the Great Plains region usually employ either a seasonal soil water balance approach, or a growth stage sensitivity approach, relative to scheduling sprinkler irrigation events. We conducted an empirical evaluation of the response of six soybean cultivars to three irrigation strategies. One was an irrigation scheduling (IS) system based solely on maintaining a soil water content in the root zone between 50% and 80% of the total plant available soil water capacity. The other two strategies involved the same depletion criterion for triggering irrigation events, except that the first irrigation was intentionally delayed until the flowering (FL) stage, or the mid-pod elongation (PD) stage. The total water amount applied during each season was approximately similar for the IS, FL, and PD strategies. Thus, the primary difference among the three strategies was the time frame during which irrigation events were scheduled. In the 1983 test, the yields attained in the IS, FL, and PD treatments were not significantly different from each other (i.e. 4.08, 4.08, and 4.04 Mg/ha, respectively), and were nearly double the yield obtained in the nonirrigated (NI) check treatment (2.29 Mg/ha). In the 1984 test, the yields of the IS, FL, and PD treatments were again not significantly different (2.02, 2.05, and 2.22 Mg/ha, respectively). However, the 1984 yield response to irrigation was also not significant relative to the NI check (1.90 Mg/ha), primarily because of low plant populations and a shorter growing season. Thus, this two-year experiment indicated that delaying irrigation until the FL or the PD stages of soybean reproductive development could be just as effective (i.e. 1983 data), or at least no more ineffective (i.e. 1984 data), in enhancing soybean yield compared to the IS strategy (Fig. 1). The soil water balance and soybean growth stage sensitivity approaches, when combined, could thus constitute an effective strategy of soybean sprinkler irrigation management in the Great Plains region.

Climate forecasts for corn producer decision making

AbstractCorn is the most widely grown crop in the Americas, with annual production in the United States of approximately 332 million metric tons. Improved climate forecasts, together with climate-related decision tools for corn producers based on these improved forecasts, could substantially reduce uncertainty and increase profitability for corn producers. The purpose of this paper is to acquaint climate information developers, climate information users, and climate researchers with an overview of weather conditions throughout the year that affect corn production as well as forecast content and timing needed by producers. The authors provide a graphic depicting the climate-informed decision cycle, which they call the climate forecast–decision cycle calendar for corn.

Skip-Row Planting Patterns Stabilize Corn Grain Yields in the Central Great Plains

The highly variable climate of the central Great Plains makes dryland corn (Zea mays) production a risky enterprise. Twenty-three field trials were conducted across the central Great Plains from 2004 through 2006 to quantify the effect of various skip-row planting patterns and plant populations on grain yield in dryland corn production. A significant planting pattern by plant population interaction was observed at only one of 23 trials, suggesting that planting pattern recommendations can be made largely irrespective of plant population. In trials where skip-row planting patterns resulted in increased grain yields compared to the standard planting pattern treatment (every row planted using a 30-inch row spacing), the mean grain yield for the standard planting treatment was 44 bu/acre. In those trials where skip-row planting resulted in decreased grain yield compared to the standard planting pattern, the mean yield was 135 bu/acre. The plant two rows, skip two rows planting pattern is recommended for riskaverse growers in the central Great Plains where field history or predictions suggest likely grain yields of 75 bu/acre or less. Planting one row and skipping one row is recommended for growers with moderate risk-aversion and likely yield levels of 100 bu/acre or less.

Irrigation Soybeans by Growth Stages in Nebraska

Irrigated soybean production in Nebraska spans a region with diverse soils and climates. Irrigators can easily adopt irrigation scheduling using a stage of growth for timing applications. However, simplifying assumptions, including soil water holding capacity, rainfall, stored soil water, and adequate irrigation system capacity, are implicit in the development of stage of growth irrigation scheduling recommendations. Reliance on these can lead to misapplication of irrigation water. This project tested irrigation scheduling techniques for indeterminate soybean production in Nebraska, with stage of growth indicating the initiation of irrigation. The range of soils and climate in the study area gave a range of irrigation scheduling recommendations. In the semi-arid, west-central Nebraska, full-season irrigation to meet evapotranspiration demand has been recommended. In sub-humid, south-central and eastern Nebraska, irrigation can be delayed until flowering on deep medium to fine textured soils if the potential root zone is filled at planting time.

Advances, Vulnerabilities, and Opportunities for Corn: A Perspective from Iowa

The central proposition of this chapter is that genetics, management, and climate have interacted to dramatically improve corn yields over time. The three factors are interrelated, confounded as the flower, fruit, and seed.

Greening of Agriculture: Is It All a Greenwash of the Globalized Economy?

Abstract Consolidation of farms, agricultural input supply companies, and commodity businesses over the past several decades have led to a concentration of ownership and control. There is growing concern by society about the environmental impacts of agriculture and the food system, and companies are eager to exploit this concern by advertising products that are environmentally friendly. When there is a greening of a company to reduce pollution or improve efficiency of non-renewable resource use, this is a legitimate way to justify advertising green products. When a company attempts to present a responsible public image, bu tdoes not change production practices we could call this a greenwashing or use of disinformation to mislead consumers. It is difficult to distinguish between the two. This chapter explores two questions: is there a relationship between scale of farming and business and green activities, and does adoption of a multiple bottom line influence greening of agriculture and food systems? After examination of the effects of farm size, we conclude that consolidation may lead to less timely field practices, separation of day-to-day management and ownership, and reduced accountability to the local community. Yet there is conflicting evidence of whether smaller farms or businesses are greener than large ones. We are convinced that a farm and a business that measure success in terms of environmental soundness and social responsibility as well as economic returns will be greener than ones that only use economics as the single bottom line. This is consistent with our discussions with farmers through Extension meetings and other contacts as well as observations we make while visiting farms in the U.S. Midwest region. Everyone agrees on the need for a greener future, but there are differences among decision makers in agriculture and food systems about how to achieve this goal.