Water Infiltration following Land Rolling of Soybeans

Land rolling of soybean fields has become a popular practice in north central and northwest Iowa during the past five years. Although this technique was first utilized to push rocks into the ground to avoid combine damage and aid in harvesting lodged crops in Canada, producers in Iowa quickly learned that pushing corn root-balls flat at the time of planting and pushing small rocks into the ground can increase harvest efficiency. Typically fields are rolled shortly after planting. One disturbing trend that was noticed, however, was that rolled fields tended to have more water standing between the rows after moderate or heavy rain events. This would imply that water infiltration was slower in fields that had been rolled compared with fields that had not been rolled. Infiltration measurements were taken on a few plots in 2010 at the ISU Northern Research Farm. It seemed that water infiltration was less on the rolled plots. However, we wanted more measurements before publishing any results. In 2011 infiltration measurements were taken on the research farm and on neighboring farms where soybeans had been rolled. The goal was to determine if water infiltration had been reduced by land rolling.

Broadcast and Band Phosphorus and Potassium Placement for Corn and Soybean Managed with Till or No Till

No-till minimizes the incorporation of crop residue and fertilizer with soil; resulting in wetter, colder soils and the accumulation of organic matter, phosphorus (P), and potassium (K) near the soil surface. Banding of P and Kcould be more effective than broadcast fertilization by counteracting stratification, applying nutrients in the root zone (starter effect), and minimizing reactions with the soil that may reduce their availability to plants. Therefore, a long-term study was established in 1994 to evaluate P and K fertilizer rates and placement methods for grain yield of corn and soybean managed with no-till and chiselplow/disk tillage.

Placement Methods of Phosphorus and Potassium for Corn and Soybean Managed with No-till and Chisel-plow/Disk Tillage

No-till management limits the incorporation of crop residue and fertilizer with soil resulting in wetter, colder soils and the accumulation of organic matter, phosphorus (P), and potassium (K) near the soil surface. Banding of P and K could be more effective than broadcast fertilization by counteracting stratification, applying nutrients in the root zone (starter effect), and minimizing reactions with the soil that may reduce their availability to plants. Therefore, this long-term study was established in 1994 to evaluate P and K fertilizer placement methods and grain yield of corn-soybean rotations managed with notill and chisel-plow/disk tillage.

Effects of Seed Treatments and a Soil-applied Nematicide on Corn Yields and Nematode Population Densities

Plant-parasitic nematodes are microscopic worms that feed on plants. Almost every nematode that feeds on corn is capable of feeding on many other plants. These nematode parasites are thought to be native to most Iowa soils and to have fed upon native plants before corn was grown as a cultivated crop. Population densities (numbers) of most species of plant-parasitic nematodes that feed on corn have to increase to damaging levels (called damage thresholds) before yield loss occurs. Products that are currently available to manage plant-parasitic nematodes on corn in the state include the soil-applied insecticide/nematicide Counter® and two relatively new protectant seed treatments, Avicta® and Votivo®. Counter® is a contact and systematic nematicide with the active ingredient terbufos. Avicta® is a contact nematicide (active ingredient abamectin) that moves on the surface of the root, and Votivo® is a special strain of the natural soil bacterium Bacillus firmus that grows on the root. Counter® is available from AMVAC, Avicta® from Syngenta Seedcare, and Votivo® from Bayer CropScience. The objective of this experiment was to assess and compare the nematode population densities and yields of corn growing in plots with and without the seed-treatment nematode protectants and the soil-applied nematicide Counter®.