Soil conditions contribute to poor plant growth

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

This article was originally published in the June 25, 2008 issue of the Vegetable CAT Alert.

The recent heavy rains have provided challenging soil conditions. Soils are compacted by intense rainfall and standing water. Excess water tends to seal the soil surface, even on some sandy soils. These conditions impede drying of the soil and movement of air into the soil. The root environment is oxygen deficient and roots cannot function properly to take up water and essential nutrients. Many beneficial microorganisms also have a difficult time functioning when oxygen starved. When these conditions persist for more than two to three days, roots will become non-functional and may begin to degrade. Cultivation is essential to open the soil and allow air to move in. Renewed aeration of the soil will stimulate root growth and microbial activity that will mineralize nitrogen and other nutrients. With aeration, new root growth will occur.

During flooded or saturated soil conditions 50 lbs N/a or more may be lost by leaching or denitrification. Once soils dry sufficiently, sidedress 40 lbs N/a to enhance root and plant growth. Spraying nitrogen and other nutrients on the foliage of stressed plants may help them get through the stress period. However, under stress conditions plants are less able to absorb nutrients through the leaves, so the benefit may not be as great as anticipated. Urea ammonium nitrate (28 percent nitrogen) is a good source of nitrogen for foliar application as long as the rate does not exceed three gallons per acre. Small amounts of nutrients may be able to be added in with other spray materials, but be sure to check compatibility.

When excess rainfall occurs, the primary nutrient of concern is usually nitrogen. In sandy soils, significant amounts of potassium may also be leached out of the root zone so that topdress application may be beneficial for high potassium requiring crops, celery and tomatoes. Boron is also subject to leaching out of the root zone in sandy soils and muck soils. For celery, celeriac, broccoli and root crops consider spraying 0.25 lb actual boron per acre on the foliage.

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