Low Corn Research Articles

The potential footprint of alternative meat adoption on corn and soybean producers

Alternative meat (AltMeat), which includes plant-based and cultured meats, has the potential to improve the global food supply chain on numerous environmental and societal dimensions. Some of these gains, derived from lower animal meat consumption, could disrupt the supply chain of crops that are used as animal feed. This study evaluates the potential impact of animal meat displacement on major corn and soybean-producing regions, globally or in developed regions. We combine trading patterns and regional cost structures with potential crop demand reductions caused by animal meat displacement, to occur by 2032 on top of an Organisation for Economic Co-operation and Development and the Food and Agriculture Organization of the United Nations (OECD-FAO) baseline projection without AltMeat. We find that potential animal meat displacement in the US and the European Union (EU) would have a minor effect on crop markets. Worldwide displacement, however, would lead to significantly lower corn and soybean prices relative to the baseline OECD-FAO projection without AltMeat. We explore quantitatively the heterogeneous impact of such developments in crop-producing regions. Our findings shed light on a trade-off associated with the significant benefits of more sustainable meat production.

Management of Weeds in Maize by Sequential or Individual Applications of Pre- and Post-Emergence Herbicides

Weeds impose serious problems in maize (corn) production, resulting in reduced crop yields and lower profits for farmers. The adverse effects of weeds have been attributed to the competition with maize plants for light, water, and nutrients, which can result in reduced growth and yield of the crop. In this context, effective weed management is important to minimize the negative impact of weeds on maize production. This can be achieved through a combination of cultural, mechanical, and chemical control methods. The use of pre-emergence and post-emergence herbicides as sequential or individual applications of these herbicides can be an effective way to manage weeds in maize. Two consecutive field experiments were conducted in 2019 and 2020 in order to determine the efficacy of sequential and individual applications of Dimethenamid-P + Terbuthylazine and Isoxaflutole + Thiencarbazone methyl + Cyprosulfamide as pre- emergence. On the other hand, Mesotrione + Nicosulfuron and Dicamba + Nicosulfuron were used as post-emergence herbicides. The effects of the herbicides were also assayed on corn yield and related parameters. In this regard, we designed the experiment in a randomized complete block design with four replications. Accordingly, the effect of the herbicides varied according to the active ingredients of the herbicide and the weed species. In addition, the effectiveness of herbicides varied according to the assessment times. The lowest effect was found on E. crus-galli, which was obtained from Mesotrione + Nicosulfuron (MN) (35%) plots. Other herbicides showed high efficacy (95–100%). Concerning values of both years, the highest cob length, cob diameter, 1000-grain weight, and plant height were obtained in weed-free control plots and the highest grain yield was obtained in the control plots with weed-free checks as 12.88 tons/ha and 12.37 tons/ha, respectively. The lowest corn grain yield was obtained in weedy control plots in both years. Our findings demonstrate that the combination of pre- and post- emergence herbicides in maize can be an effective way chemical weed control option.

Nutrition Impact Symptoms in Relation to Head and Neck Cancer Survivor’s Vegetable Intake and Use of Seasoning

Background: Most head and neck cancer (HNC) patients undergoing aggressive treatments with chemoradiotherapy and surgical resection of tumors suffer from symptoms long after treatment is completed that hinder adequate oral food intake, collectively known as Nutrition Impact Symptoms (NIS). Our aim was to examine the correlations between NIS and HNC survivors’ vegetable intake and use of seasoning. Methods: We conducted a 29-item telephone administrated survey to collect vegetable intake and seasoning habits among HNC survivors (n=22, age 61.4 ± 9.8 years, mean ± standard deviation) who received radiation therapy between 6 months and 10 years before recruitment identified through the cancer registry at Carle Foundation Hospital. Treatment-related side-effects (11 items) including difficulty swallowing, dry mouth, and mouth sores reflected NIS. A mean composite score was created for all the symptoms where higher scores indicated greater NIS. Spearman correlations examined the relationships between NIS, vegetable intake, and seasoning. Results: Half (50%) of the participants reported no change in their vegetable intake since diagnosis of cancer, and on average, ate 1 cup/day of total vegetables. Higher NIS scores associated with higher pumpkin and sweet potatoes intake (r (20) = .43, p<0.05), and there was a trend for higher scores of difficulties swallowing to be associated with lower corn and peas intake (r (20) =-.37, p=0.08). Participants with higher scores of problems with teeth and gums were less likely to use seasoning (r (20) = -.42, p<0.05). Conclusion: The findings support that HNC treatment can affect vegetable intake long after completion of radiotherapy. However, it would be premature for any recommendations to be derived from the present study for health professionals. A larger, observational study with a longer follow-up is therefore needed to examine these correlations.

Corn response to selected soil health indicators in a Texas drought

The phrase “soil health” describes the condition of a soil in terms of its physical, chemical, and biological properties. The relationship between soil health and crop yield is rather complex, and quantifying their spatial characteristics at field scale is often limited in the literature. To explore the significance and spatial characteristics of soil health and its indicators in crop production, field-based research was conducted in 2018 at the Blackland Research Center, Texas with the following objectives: (i) to quantify soil health indicators of the Haney Soil Health Tool across a corn field; (ii) to relate soil health status to drought-year corn yield using geospatial techniques; and (iii) to evaluate the relationship among soil health, corn yield, and soils types. We collected 218 samples from 0 to 10 cm soil depth in a 27-ha field following a 35 m × 35 m grid sampling scheme. Samples were analyzed for water extractable organic carbon (WEOC), total nitrogen, nitrate-nitrogen, ammoniacal-nitrogen, and 24-hr CO2 evolution (1-day CO2). Analyses results were used to calculate a soil health value based on Haney Soil Health Tool. The field had an average soil health value of 8.5 (±2.2), and corn yield of 2.9 t ha−1 (±1.3); however, corn yield was more variable (CV > 43%) than soil health (CV = 26.7%). Overall, soil samples with lower values of 1-day CO2, WEOC, and organic nitrogen indicated a lower soil health value, which generally corresponding to lower corn yield. Corn yield may be weakly predicted by soil health (Corn yield = −0.29 + 0.39 × Soil health value, R2 = 0.28). Soil type and rainfall exhibited measurable effects upon the calculated soil health value; corn yields were greater for Houston Black clay than Austin silt clay under drought-year conditions. The variation in drought-year corn yield can be explained by the soil health and its indicators in Texas Blackland soils. Further research is necessary to verify the relationship in differing soil types, management scenarios, and annual rainfall totals.

Combining Ability of Husk Extension, Maysin Content, and Corn Earworm Resistance

Corn earworm (Helicoverpa zea) is a destructive pest with limited management options in sweet corn (Zea mays) production. Increased husk extension and the presence of the C-glycosyl flavone maysin are two proposed mechanisms for improving corn earworm resistance in corn cultivars. A factorial mating design was conducted to test hybrid combinations of sweet corn inbreds with long husks and/or maysin to identify candidates for future cultivar development. The mating design had seven male parents, including three commercial sweet corn inbreds (Wh9261, We11401, and Wt1001) and four inbreds selected for maysin content (Maysin1, 2, 3, and 4), and five female parents, including two commercial sweet corn inbreds (Ia453su and Ia5125su) and three inbreds with long, thick, tight husks (A684su, A685su, and A686su). Hybrids were evaluated for ear length, husk length, maysin content, and corn earworm resistance at six environments in 2016 and 2017. Relationships between husk extension, maysin, and corn earworm resistance were inconsistent, but five inbreds produced hybrids with significantly lower corn earworm infestation and/or damage, demonstrating potential to confer resistance to the corn earworm.

The threat of oil market turmoils to food price stability in Sub-Saharan Africa

Abstract While the causal relationship between different types of oil shocks and food prices in the US and other developed countries has been extensively studied, the inter-dynamics between global oil market turmoils and food prices in Sub-Saharan Africa (SSA) remain unclear. This gap in the literature is particularly striking as populations in developing countries are much more vulnerable to food crises than those in developed countries. In this paper we use structural vector autoregressive (SVAR) models to investigate the impacts of global oil market shocks on local corn prices in several SSA countries. We estimate the structural shocks through independent component analysis, which allows for a more agnostic identification compared with conventional methods. Our key findings are that unlike US or global corn markets, African corn markets are much less sensitive to the impacts of oil-specific demand shocks, instead, disruptions in global oil supply can lead to an increase in food prices in several markets. Countries suffering from oil-supply shocks have neither strategic or natural oil reserves to buffer import shortages, nor efficient oil distribution systems that translate into food prices through higher transport costs. We show that a large share of corn price surges in 2011 and 2012 can be attributed to oil-supply shortages caused by the Libyan revolution and the oil embargo against Iran. Conversely, the shale oil boom in the US and the oil production expansion in the Middle East exerted downward pressures on corn prices in three African countries in 2014/15. Finally, political events related to the oil market, e.g. the tensions between the US and Iran or the recent oil price war between Saudi Arabia and Russia, have the potential to raise or lower corn prices by up to 25%.

Cross-scale evaluation of dynamic crop growth in WRF and Noah-MP-Crop

Accurately representing croplands in climate models is important for simulating water and energy fluxes between the land and atmosphere, as well as evaluating the impacts of climate change on agriculture. The recent integration of dynamic crop growth in the Noah land surface model with multiparameterization (Noah-MP-Crop) has the potential to substantially advance Earth system modeling and is included in the latest release of the Weather Research and Forecasting (WRF) regional climate model. The addition of dynamic crop growth to WRF provides a unique opportunity to simultaneously evaluate biases associated with a crop model coupled to a regional climate model and address outstanding questions regarding the role of agroecosystems in modulating regional climate. Here, we analyze dynamic crop growth in WRF across three simulated spatial scales (25km, 5km, and 1km) for growing seasons with precipitation above (2010), below (2012), and approximately equal (2015) to the seasonal average. Including dynamic crop growth in WRF significantly reduces biases in simulated leaf area index over croplands in the central U.S. relative to observations. However, there is no substantial difference in calculated daily evapotranspiration, average growing season temperature, or total growing season precipitation between WRF simulations with dynamic crops (WRF-Crop) compared to the dynamic vegetation module without crops (WRF-DV). Simulated corn (soy) mean absolute error (MAE), as a percentage of observed annual average yield, ranges from 24.7% -101% (28.1% - 109%) depending on year and spatial resolution, with the most significant biases in highly irrigated counties. Forcing Noah-MP-Crop with observed climate substantially reduces the range of corn (soy) yield MAE to 9.5% - 55.1% (15.0% - 37.5). Increased model resolution consistently leads to lower corn and soy yield estimates within WRF-Crop.

The Competitive Impact of Cooperatives on the Spot Market: A Spatial Analysis of Iowa Corn Prices

Abstract Imperfect competition in the agricultural input procurement market is prevalent, especially at the local and regional scale. While there is much theoretical work on the positive effect of cooperatives on spatial competition, applied research is relatively scarce. We address the gap in the literature with an empirical study of cash prices in the Iowa corn market. With 589 observations from the 2018 harvest season, we construct a spatial model of price competition among grain handlers within a 20-mile radius. Among other findings, we conclude the ownership structure of Iowa grain handlers is important to explain the spatial dependence in corn cash prices. On average, cooperative grain handlers offer a lower corn cash price as compared to corporate grain handlers (¢1.20–1.72 per bushel), which is likely offset by refunds and dividends at the end of the fiscal year. At the same time, cooperative grain handlers force an adjustment in the behaviour and pricing strategy of nearby competitors. Cooperative grain handlers on average facilitate a significant increase of ¢0.65–2.08 per bushel in the corn cash price of competitors within a 5–17 mile radius. Our novel findings inform recommendations in terms of spatial entry and location decisions by cooperative grain handlers.

The Effect of Technological Progress, Demand, and Energy Policy on Agricultural and Bioenergy Markets

This study investigates the consequences of agricultural technological progress, biofuel policy, and agricultural demand growth on crop, livestock, and bioenergy markets, as well as resource usage and greenhouse gas (GHG) emissions, over data in the United States. We formed scenarios for future technological progress, demand growth, and biofuel policy and carried out a dynamic simulation. The major findings are: (1) Increasing technological progress reduces cropland for biofuel and cropland pasture for livestock but increases cropland for crop production; (2) Reducing corn ethanol requirements causes more cropland to move from cropping to pasture uses for livestock, however, lowering ethanol from corn residue has minor effects on cropland use; (3) Lowering the requirement of ethanol from corn lowers the price for most of the field crops and meat commodities, especially corn, hay, sorghum, and non-fed beef; (4) Technological progress and biofuel policy have significant effects of on GHG emissions. Increasing technical progress reduces overall GHG emissions. A lower corn ethanol level results in much larger GHG emissions as compared with the control case. This implies producing corn ethanol is effective in reducing emissions; and (5) Technological improvement is a key factor in meeting growing global demand for food and energy and reducing emissions.

Effect of Cover Crop Termination Timing on Pools and Fluxes of Inorganic Nitrogen in No‐Till Corn

Cover crops are increasingly used around the world to enhance N cycling and provide a suite of agroecosystem benefits. The N scavenging capacity of cover crops during winter months is well recognized. Our research characterized spring management effects (e.g., early vs. late termination) on cover crop biomass, decomposition and N release rates, inorganic soil N, soil water dynamics, and corn (Zea mays L.) performance. Cereal rye (Secale cereale L.) was established in Beltsville, MD, to evaluate three management scenarios: no cover crop; early termination (∼40 d before corn planting); late termination (∼7 d before corn planting). Cereal rye biomass was quantified before termination, and decomposition was tracked over a 24‐wk period to assess loss. Soil N content to 100 cm, soil volumetric water content, and corn performance were evaluated over the corn growing season. Low spring precipitation in 2016 led to similar amounts of cereal rye biomass for early and late termination; however, late‐terminated cereal rye had lower quality biomass (higher C/N) in both years, leading to slower decomposition and N release rates. Over the corn growing season, late‐terminated cereal rye consistently had smaller soil N pools, suggesting more efficient N cycling (better synchrony of N release from cover crop residues with corn N demand) than early‐terminated cover crops. Corn yields were smallest following late‐terminated cereal rye in 2016, but there was no difference in yields among cover crop treatments in 2017. Overall, we conclude that planting cereal rye cover crops and delaying termination until later in the season will help retain and efficiently cycle N while maintaining high corn yields.Core Ideas We tested the effect of cover crop termination timing on N dynamics before corn. Late‐terminated cereal rye had slower rates of biomass loss and N release. Larger soil N pools in 2017 than 2016 resulted from lower corn yields. Cover crop biomass and corn performance were influenced by precipitation levels. Nitrogen was more efficiently cycled in systems with cover crops than systems without cover crops.

Spatial variability of soil physical attributes in integrated production systems in the Amazon region

Abstract: The objective of this work was to analyze the spatial variability of soil physical attributes in integrated production systems and its relationship with the growth and yield of a corn (Zea mays) crop intercropped with palisade grass (Urochloa brizantha). The experiment was carried out in an integrated crop-livestock (ICL) system and in an integrated crop-livestock-forestry (ICLF) system, in a Plinthic Hapludox. The ICLF system was managed in alleys between eucalyptus (Eucalyptus spp.) rows, spaced at 18, 30, and 42 m. Corn grain and forage yields were positively correlated with soil clay and moisture contents, whereas grain yield was negatively correlated with soil penetration resistance. The lowest corn plant heights and grain yields were observed near eucalyptus rows. The average values for soil penetration resistance were below 2.0 MPa. Spatial variability was verified for: corn plant height, grain yield, and agronomic efficiency; forage intercropping; and soil moisture and silt contents, as well as penetration resistance. Greater grain and biomass yields were obtained at a 42-m distance between tree rows. The obtained results are indicative that corn traits and soil physical attributes were only slightly associated. The spatial distribution of the eucalyptus rows influences the agronomic efficiency of the intercrop and soil moisture contents.

Corn Emergence and Yield Response to Row-unit Depth and Downforce for Varying Field Conditions

Abstract. Optimum row-crop planter seeding depth performance is required to place seeds within proper soil conditions to ensure quick germination and maximize the likelihood of uniform emergence. Seeding depth is adjusted prior to planting by selecting a row-unit depth, followed by the adjustment of a row-unit downforce for proper seed-soil contact. Optimum row-unit depth and downforce settings required to maintain a consistent seeding depth are variable. The objective of this study was to evaluate corn ( L) emergence and yield response to row-unit depth and downforce in changing field conditions between sites and growing seasons. Corn was planted with a 6-row John Deere MaxEmerge Plus planter equipped with heavy duty downforce springs. The experiment was conducted in 2014 and 2015 in Central Alabama for non-irrigated corn. Two fields, three row-unit depths (4.4, 7.0, and 9.5 cm), and three row-unit downforce settings (0.0, 1.1, and 1.8 kN) were evaluated. Emergence was measured at 75 and 100 Growing Degree Days (GDDs). Yield was measured using a yield monitor installed on the combine harvester. Corn emergence was mainly affected by changes in weather conditions. Row-unit depth and downforce did not affect corn emergence in warmer weather conditions but the 4.4 cm row-unit depth resulted in more emergence than the other row-unit depth settings in cooler weather conditions. Yield ranged from 8,000 to 13,000 kg ha-1 across treatments and yield was mostly affected by changing growing conditions between fields and growing seasons. Plant population significantly varied with treatments, but lower plant populations did not always result in lower corn yields. These findings provided a better understanding of corn emergence and yield response to row-unit depth and downforce in varying field conditions. Keywords: Corn, Depth, Downforce, Emergence, Maize, Planter, Yield.

Streaming Urea Ammonium Nitrate with or without Enhanced Efficiency Products Impacted Corn Yields, Ammonia, and Nitrous Oxide Emissions

Core Ideas Streaming urea ammonium nitrate resulted in 11% lower corn yields compared to injected urea ammonium nitrate.Ammonia volatilization (NH3) begins immediately after application for streaming urea ammonium nitrate.In 2015–2016, NH3 loss was 3.6 fold greater for streaming urea ammonium nitrate compared to injected urea ammonium nitrate.Urease and nitrification inhibitors did not increase corn yields with streaming urea ammonium nitrate.Streaming urea ammonium nitrate with a urease inhibitor increased N2O emissions by 18.7%. Surface streaming urea ammonium nitrate (UAN) into corn (Zea mays L.) at side‐dress (v4–v6) or later in the season (v12–v14) is an emerging N fertilizer application method as it is rapid, reduces soil disturbance, and allows for flexible application times. In 2013 and 2014, side‐dress N application (130 kg N ha−1) using three streaming UAN sources was evaluated for their ability to maintain grain yield, reduce ammonia (NH3) volatilization, and mitigate nitrous oxide (N2O) emissions. The products included streaming of urea ammonium nitrate (StrUAN), urea ammonium nitrate with a urease inhibitor (StrUAN‐UI), urea ammonium nitrate with urease inhibitor plus nitrification inhibitor (StrUAN‐UI+NI), and a control (no N). The efficacy of streaming relative to traditional shallow‐injected urea ammonium nitrate (InjUAN) was also assessed. Delayed NH3 sampling related to wind‐tunnel installation in 2013 and 2014 led to additional NH3 measurements in 2015 and 2016. Average yields from StrUAN were 11% lower relative to InjUAN. The use of inhibitors did not improve yields relative to StrUAN. Ammonia volatilization was not significantly different between StrUAN and InjUAN losing 14 and 20% of applied N (2‐yr average), respectively. However in 2015 and 2016, NH3 volatilization from StrUAN was 3.6‐fold greater than InjUAN when measurements were started immediately after application. Hence lower yields in 2013 and 2014 from StrUAN likely reflect N loss to rapid volatilization during or shortly after application. The StrUAN‐UI treatment increased 2‐yr average N2O emissions by 17.3 to 18.7% relative to StrUAN or StrUAN‐UI+NI. For humid‐temperate clay loam soil, UAN streaming with/without inhibitors was not effective for maintaining yields or reducing NH3 volatilization.

THE COMPETITIVENESS OF MANUAL AND MECHANIZED CORN CULTIVATION

In 2015, total imports of corn in Indonesia reached 3.1 million tons due to lower corn production of Indonesia. One way to overcome this is to apply the technology mechanization in the cultivation process as practiced by the country largest corn producer in the world. The purpose of this study is to know the level of competitiveness of mechanized corn cultivation and manual. In addition, it is to determine the effect of government policy on competitiveness of both type of corn cultivation. The analytical method used is the Policy Analysis Matrix (PAM). The analysis showed that mechanized corn cultivation is competitive so that the business is feasible to be developed. It is seen from the DRC and PCR- corn agribusiness based on mechanization level values that less than one is 0.54 and 0.50. The manual corn cultivation, however, only show a competitive advantage but does not have a comparative advantage. Output policy is a policy that better influence both type mechanized and manual corn cultivation. Keywords: competitiveness, corn, Policy Analysis Matrix (PAM)

Green Manure Comparison between Winter Wheat and Corn: Weeds, Yields, and Economics

Red clover (Trifolium pratense L.) and hairy vetch (Vicia villosa Roth) are leguminous crops (“green manure” hereafter), widely studied for their N2‐fixing contributions to cropping systems. Under certain circumstances they can provide weed control in cash crops. This study compared weed control, crop yields, herbicide use, and economic performance of these green manures in a no‐till winter cereal–green manure–corn (Zea mays L.) silage cropping sequence in central Pennsylvania. Red clover was interseeded into winter wheat (Triticum aestivum L.) or rye (Secale cereale L.), while hairy vetch and triticale (X Triticosecale) were planted after winter cereal harvest. Compared to hairy vetch, red clover provided continuous soil cover between the winter cereal and corn and two herbicide applications could not be applied (one in wheat and one prior to seeding hairy vetch) to the red clover, reducing herbicide active ingredient use by 28%. Weed infestation in wheat and corn did not differ between green manure systems, but corn yield following red clover averaged 3320 kg ha−1more, and 2012 wheat yield was 180 kg ha−1 greater in the red clover sequence. Corn after hairy vetch–triticale had lower corn plant population in 2012–2013. Yield differences in corn in 2012 probably resulted from population differences. Primarily because of red clover forage value, the red clover system resulted in greater net returns to management by US$1360 ha−1, and even without the forage harvest, the red clover system would have been more profitable due to lower production costs.Core Ideas As a green manure, red clover provided multiple benefits over hairy vetch and triticale. Red clover underseeded in winter grain, produced continuous cover, forage, and higher corn yield. Compared to hairy vetch and triticale, red clover controlled weeds with less herbicide. Red clover was more profitable than hairy vetch.

Effect of Dietary Starch Source and Concentration on Equine Fecal Microbiota.

Starch from corn is less susceptible to equine small intestinal digestion than starch from oats, and starch that reaches the hindgut can be utilized by the microbiota. The objective of the current study was to examine the effects of starch source on equine fecal microbiota. Thirty horses were assigned to treatments: control (hay only), HC (high corn), HO (high oats), LC (low corn), LO (low oats), and LW (low pelleted wheat middlings). Horses received an all-forage diet (2 wk; d -14 to d -1) before the treatment diets (2 wk; d 1 to 14). Starch was introduced gradually so that horses received 50% of the assigned starch amount (high = 2 g starch/kg BW; low = 1 g starch/kg BW) by d 4 and 100% by d 11. Fecal samples were obtained at the end of the forage-only period (S0; d -2), and on d 6 (S1) and d 13 (S2) of the treatment period. Cellulolytics, lactobacilli, Group D Gram-positive cocci (GPC), lactate-utilizers and amylolytics were enumerated. Enumeration data were log transformed and analyzed by repeated measures ANOVA. There were sample day × treatment interactions (P < 0.0001) for all bacteria enumerated. Enumerations from control horses did not change during the sampling period (P > 0.05). All treatments except LO resulted in increased amylolytics and decreased cellulolytics, but the changes were larger in horses fed corn and wheat middlings (P < 0.05). Feeding oats resulted in increased lactobacilli and decreased GPC (P < 0.05), while corn had the opposite effects. LW had increased lactobacilli and GPC (P < 0.05). The predominant amylolytic isolates from HC, LC and LW on S2 were identified by 16S RNA gene sequencing as Enterococcus faecalis, but other species were found in oat fed horses. These results demonstrate that starch source can have a differential effect on the equine fecal microbiota.

Field‐Scale Evaluation of Poultry Manure as a Combined Nutrient Resource for Corn Production

An on‐farm study was conducted in Iowa from 2004 to 2006 at 18 sites to evaluate corn (Zea mays L.) grain yield (GY) and soil‐ and plant‐test responses to poultry manure (PM) nutrient application at the field scale. A control and two target PM rates based on total N (PM‐N) were applied in randomized field‐length strips with three replications. Corn GY responded positively to PM applications. While N, P, and K plant and soil tests were related to PM nutrient rates, there was considerable variation, and relationships were probably influenced by the multiple applied nutrients. Soil‐test P and soil‐test K across sites increased linearly with increasing PM total P and K rates and with large increases from the high rates. This confirms high P and K crop availability. Grain yield responses to PM decreased linearly with increasing leaf chlorophyll meter (CM) and late spring soil NO3–N test (LSNT) values but were not related to end‐of‐season lower corn stalk NO3–N test values. No N test had a plateau relationship with GY, suggesting no excess N supply despite large PM‐N rates. This confirms low first‐year PM‐N availability. The relationship between CM and LSNT indicated a critical LSNT value at 24 mg kg−1, similar to that from previous small‐plot research. This field‐scale study showed that PM is a valuable nutrient resource. However, due to PM multinutrient content and differences in availability, the nutrient causing GY and plant‐ or soil‐test results often cannot be clearly identified and results need careful interpretation for reliable use.

HIGH-SPEED CULTIVATION AND BANDING FOR WEED MANAGEMENT IN NO-TILL CORN

Replacing herbicides with mechanical cultivation can reduce pesticide use in row crop production. Although a majority of Iowa’s corn land is cultivated, most is cultivated only once and herbicide is broadcast applied. To increase grower confidence in reducing herbicide use and in using cultivation for interrow weed control, a three-year field experiment compared various single-cultivation plus band-herbicide application strategies with broadcast application strategy and no-control strategy. To cover larger acreages in a narrow window of time, cultivation speed was increased each year from 11.3 to 14.1 to 16.9 km/h (7.0, 8.8, and 10.5 mph). A 38-cm (15-in.) herbicide band treatment had less weed growth, and generally greater yield, extended leaf height, and corn population than did a 19-cm (7.5-in.) band treatment. Few differences were noted among cultivator styles. Weed management and grain yield were as good or better with the traditional low-crown sweep as with other styles. Its wider cutting width (56-cm or 22 in.) in 76-cm (30-in.) rows resulted in a lower corn population, however, when operated at 16.9 km/h (10.5 mph) with a crosswind. Differences in weed population and visual weed cover rankings when comparing single-cultivation with broadcast-only strategies varied with years. Grain yield from a treatment using a single cultivation with a low-crown sweep and a 38-cm (15-in.) wide herbicide band was statistically equivalent to that from a broadcast-only treatment in all three years. Results of this study indicate that herbicide use can be halved and weed control and corn yield can be maintained by use of a 38 cm (15 in.) herbicide band and a single sweep cultivation.

Effects of Japanese Beetle (Coleoptera: Scarabaeidae) and Silk Clipping in Field Corn

Japanese beetle (Popillia japonica Newman) is an emerging silk-feeding insect found in fields in the lower Corn Belt and Midsouthern United States. Studies were conducted in 2010 and 2011 to evaluate how silk clipping in corn affects pollination and yield parameters. Manually clipping silks once daily had modest effects on yield parameters. Sustained clipping by either manually clipping silks three times per day or by caging Japanese beetles onto ears affected total kernel weight if it occurred during early silking (R1 growth stage). Manually clipping silks three times per day for the first 5 d of silking affected the number of kernels per ear, total kernel weight, and the weight of individual kernels. Caged beetles fed on silks and, depending on the number of beetles caged per ear, reduced the number of kernels per ear. Caging eight beetles per ear significantly reduced total kernel weight compared with noninfested ears. Drought stress before anthesis appeared to magnify the impact of silk clipping by Japanese beetles. There was evidence of some compensation for reduced pollination by increasing the size of pollinated kernels within the ear. Our results showed that it requires sustained silk clipping during the first week of silking to have substantial impacts on pollination and yield parameters, at least under good growing conditions. Some states recommend treating for Japanese beetle when three Japanese beetles per ear are found, silks are clipped to < 13 mm, and pollination is < 50% complete, and that recommendation appears to be adequate.

Intercropping Time of Corn and Palisadegrass or Guineagrass Affecting Grain Yield and Forage Production

ABSTRACTIntercropping corn (Zea mays L.) with forages, such as palisadegrass {Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster [syn. Brachiaria brizantha (Hochst. ex A. Rich.) Stapf]} or guineagrass [Megathyrsus maximus (Jacq.) B. K. Simon &amp; S. W. L. Jacobs (syn. Panicum maximum Jacq.)], provides large amounts of biomass for use as straw in no‐tillage systems or as pasture. However, it is important to evaluate what time these forages have to be sown into corn systems to avoid reductions in both corn and forage production. This study, conducted for three growing seasons at Botucatu, Brazil, evaluated nutrient concentration and yield of corn as affected by time of forage intercropped as well as forage's dry matter production. Our data showed that intercropping systems did not reduce leaf nutrient concentrations and grain yield of corn in relation to sole corn. The simultaneous intercropping of corn and guineagrass resulted in the lowest plant population (51,200 plant ha−1), number of ears per plant (1.0), and, consequently, the lowest corn grain yield (9801 kg ha−1). Guineagrass seeded at the time of corn fertilizer topdressing resulted in the highest plant population (59,400 plants ha−1), number of ears per plant (1.2), and corn grain yield (12,077 kg ha−1). Forage production was highest when intercrop was done simultaneously. Palisadegrass could be intercropped with corn both simultaneously or at topdressing fertilization stage. In contrast, it is recommended that guineagrass should only be intercropped with corn at topdressing fertilization.