Corn Production Area Research Articles

Atrazine and nitrate levels in the ground water of irrigation wells in the agricultural area of chamusca (Portugal)

Atrazine and nitrate levels found in ground water samples from an unconfined aquifer in the agricultural area of Chamusca (Portugal) are reported. High levels of both, atrazine (0.3–0.4 μg/L) and nitrates (≍100 mg/L) were found in Azinhaga area, located downstream to the main corn production area.

Relating United States Crop Land Use to Natural Resources and Climate Change

Crop production depends not only on the yield but also on the area harvested. The yield response to climate change has been widely examined, but the sensitivity of crop land use to hypothetical climate change has not been examined directly. Crop land-use regression models for estimating crop area indices (CAIs)-the percent of land used for corn, soybean, wheat, and sorghum production-are presented. Inputs to the models include available water-holding capacity of the soil, percent of land available for rain-fed agricultural production, annual precipitation, and annual temperature. The total variance of CAI explained by the models ranged from 78% from wheat to 87% for sorghum, and the root-mean-square errors ranged from 1.74% for sorghum to 4.24% for corn. The introduction of additional climatic variables to the models did not significantly improve their performance. The crop land-use models were used to predict the CAI for every crop reporting district in the United States for the current climatic condition and for possible future climate change scenarios (various combinations of temperature and precipitation changes over a range of -3{degrees} to +6{degrees}C and -20% to +20% respectively). The magnitude of climatic warming suggested by GCMs (GISS and GFDL) is from 3.5{degrees} to 5.9{degrees}C for regionsmore » of the United States. For this magnitude of warming, the model suggests corn and soybean production areas may decline while wheat and sorghum production areas may expand. If the warming is accompanied by a decrease in annual precipitation from 1% to 10%, then the areas used for corn and soybean production could decrease by as much as 20% and 40%, respectively. The area for sorghum and wheat under these conditions would increase by as much as 80% and 70%, respectively; the exact amount depending strongly on the change in precipitation. 15 refs., 6 figs.« less

Leaching of Atrazine in the Root Zone of an Alluvial Soil in Nebraska

AbstractLeaching of atrazine [2‐chloro‐4‐(ethylamino)‐6 (isopropylamino‐s‐triazine] was measured from the soil surface to below the root zone in an irrigated field under continuous corn (Zea mays L.). The field was located in the Platte River Valley of central Nebraska in the central Great Plains area of the USA. This nearly level site is typical of the Platte River Valley with a coarse‐ to medium‐textured soil of alluvial origin that contains low levels of organic matter, and with a water table at a 5‐m depth. Vacuum soil water extractors located 1.5 m below the soil surface recovered an average of 0.072% of the atrazine applied to the surface during 1979 and 1980. Analysis of groundwater recovered from wells on opposite ends of the experimental field indicated enrichment with atrazine in the direction of the hydraulic gradient. Results support direct downward leaching as largely responsible for the low‐level atrazine contamination detected in groundwater throughout the irrigated corn production areas of the valley.

Weed Control in Corn Planted into Untilled Winter Wheat Stubble1

AbstractAs reduced tillage production systems expand in the Great Plains, a critical need will be non‐tillage methods for controlling established weeds prior to planting the crop. This research dealt with finding selective weed control methods for corn (Zea mays L.) in an ecofarming system consisting of a winter wheat (Triticum aestivum L.)‐corn‐fallow rotation on a Sharpsburg silty clay loam (Typic Argiudolls) at Lincoln and a Holdrege silt loam (Typic Argiustolls) at North Platte, Nebraska. Both established and subsequently emerging weed species must be selectively controlled without tillage in order to better conserve the soil, water, energy, and labor requirements in this marginal corn production area. This research has as an objective the moving of dryland corn production further west in the Great Plains region. Adequate control of annual grass weeds as a group was more difficult than control of broadleaf weeds. The more difficult to control weed species were velvetleaf (Abutilon theophrasti Medic.), fall panicum (Panicum dichotomiflorum Michx.), large crabgrass [Digitaria sanguinalis (L.) Scop.], and clammy groundcherry (Physalis heterophylla Nees). Weed yields were the lowest and corn yields were the highest on plots receiving atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] at 2.2 kg/ha, cyanazine (2‐[[4‐chloro‐6‐(ethylamino)‐s‐triazin‐2‐yl]amino]‐2‐methyl‐propionitrile) at 2.8 kg/ha, or a combination of the two at 0.9 + 1.9 kg/ha. Four foliar‐active herbicide treatments—2,4‐D [(2,4‐dichlorophenoxy)acetic acid] at 1.1 kg/ha, 2,4‐D at 1.1 kg/ha + 9.4 liters/ha Sunspray 11E oil, paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) at 0.3 kg/ha, and glyphosate [N‐(phosphonomethyl)glycine] at 0.6 kg/ha—were equally effective for controlling established weeds and maintaining high corn yields when combined with the s‐triazine herbicides. The no‐till farmer has a number of herbicides available which will selectively destroy established and subsequently germinating weed species in corn without tillage.