High rainfall amounts lead to loss of nitrogen from the soil. Sometimes the loss is great enough that a crop will benefit from additional nitrogen application. This article will describe how nitrogen is lost and factors to consider in deciding whether to apply extra nitrogen. There are two main ways nitrogen is lost from wet soils. Nitrogen is lost to the air by denitrification. Denitrification occurs in saturated soils when there is little oxygen in the soil. In the denitrification process, nitrate is broken down by bacteria to form oxygen and volatile nitrogen compounds including nitrous oxide and nitrogen gas. These volatile compounds move into the air and nitrogen is lost from the soil. Denitrification is common on heavier soils. In Indiana, saturated soils lose 4% to 5% of their nitrate nitrogen for each day they are saturated. Nitrogen is lost below the root zone of the crop by leaching.[Read More…]
34 articles tagged "Soil Fertility and Fertilizers".
Purdue University’s Boiler Hop Yard has started its second growing season with the hopes of providing Indiana growers with science-based recommendations for hop production in the Midwest. With summer rapidly approaching, hop bines are now climbing over 10 feet high in portions of Indiana, and the Boiler Hop Yard is no exception. Downy Mildew. One of the biggest threats to Indiana hop production is downy mildew. Downy mildew (Pseudopernospora humuli) can cause hop quality to depreciate, yield to be stunted, and sometimes even plant death. Downy mildew was identified in the Boiler Hop Yard in mid-April this year, and is present in other Indiana hop farms as well. Downy mildew overwinters in the crown of the hop plant, and appears in the early spring on newly emerged primary basal or aerial spikes as a sidearm (Figure 1). These spikes have irregular growth patterns and are undesirable in hop production. The[Read More…]
Cover crops should be killed at least a couple of weeks before planting vegetables. That will give the cover time to partially decompose, and time for any cutworm larvae that may be in the crop to die or pupate. If wet weather delays killing or incorporation of cover crops, the time between incorporation and planting may be shorter than normal, or the cover crop may be larger than normal. There are implications for pest, nutrient, and cover crop management. Black cutworm moths prefer to lay eggs in vegetated areas, including fields with cover crops or weeds. They typically show up in early May. To track black cutworm moth catches in pheromone traps throughout the state, refer to the Purdue Pest & Crop Newsletter at http://extension.entm.purdue.edu/pestcrop/2015/index.html. If larvae are present in the cover crop and they survive until the cash crop is planted or emerges, they may cause serious stand loss.[Read More…]
Sometimes newly transplanted crops don’t take off like we’d expect. Consider the newly transplanted tomato seedlings in these images. In Figure 1, lower leaves are chlorotic (yellow) and leaflet edges and leaves curl downward. In Figure 2, lower leaves are chlorotic or bleached and some had necrotic (dead) spots. In Figure 3, some leaves have died and others have ‘scorched’ margins or tips. Figures 1 and 2 are from a high tunnel; Figure 3 is from the field. What they have in common is that the tomato plants are not thriving after transplanting. It may be hard to say exactly what is going on with each of these, but it would not be surprising if they were cases of over application of a fertilizer or soil amendment, leading to toxicities for the plant. Ammonium toxicity is common when soil is cool and wet, soil pH is low, and there is[Read More…]