ISSUE 5   June 12, 2008


During the end of May and beginning of June a number of rain events changed the Red River landscape from being without visible water in the ditches to high water levels in the rivers, ditches and some standing water in lower areas of the fields. Excess moisture can cause overland flooding, waterlogged conditions, and high water tables. This excess soil moisture can result in changes in physical and chemical properties in the root zone. The respiration of plant roots, soil micro-organisms and fauna leads to rapid exhaustion of soil oxygen. Whenever the plant faces prolonged (>34 days) excess soil moisture conditions, the plant roots suffer extreme oxygen stress. The extent of damage due to excess moisture stress varies between crops and also depends on the developmental stage of the crop. Just emerging plants are more susceptible than established plants. Dry beans are very susceptible to excess moisture. Corn is susceptible to excess moisture stress during the early seedling to tasseling stage. Soybeans have been somewhat tolerant to short periods of excess moisture.

As most crops are still in the early stages of development, producers will soon be anxious to go back into the field for crop management purposes. However, there is a danger for soil compaction, which may occur when pressure from farm equipment on the surface of wet soils forces air out of pore spaces in the soil. Wet soil has much less resistance to compaction than dry soil. When the soil is just dry enough to go into the field the potential for compaction is greatest. Low pressure tires, large flotation tires, or dual wheels may help reduce surface compaction. However, any machinery traffic on a waterlogged field will cause subsoil compaction the heavier the load, the greater the impact. Compacted soil reduces root growth and the movement of water and air through the soil. Once the soil is compacted it is difficult to get it back in good shape. Prevention of compaction is easier than trying to manage compact soils.



Due to the high cost for seed a number of producers have gone back to seeding soybeans in rows. Cultivation is a tool to use in controlling weeds. Sunflower, corn, soybean , dry bean crops and weeds compete for soil moisture and nutrients. Early season competition causes greater yield losses than at any other time during the growing season. Early cultivation when annual weeds are small is most effective. Use a cultivator which is set shallow to control weed sprouts as they emerge and start to grow. A shallow cultivation operation will also limit crop root pruning and avoid bringing new weed seeds to the top. Cultivating too deeply can cause the dilution of previously applied preemergence herbicides and therefore reducing the effectiveness of the herbicide. Shallow cultivation can be repeated to control any newly germinating weeds. Avoid excessive ridging of the rows especially in soybeans, navy and pinto beans which need level ground at harvesting.

Hans Kandel
Extension Agronomist - Broadleaf Crops



That the weather this spring is cool is not news, but now that we are six weeks into the corn growing season the magnitude of the lag in corn development is becoming a concern. Based on a May 1st planting date, we are now running between 80 and 143 corn growing degree days (GDDs) behind the long term average, depending on the region of the state (see following table). Since GDDs typically accumulate at the rate of 13 per day in early June, this means that we are currently about six to seven calendar days behind normal corn development. Furthermore, this means that corn is 1.0 to 1.5 leaves behind normal (about 85 GDDs are required for each new leaf that develops). It is still early in the season and there is certainly potential for crops to catch up if temperatures during the remainder of the season are above normal. Nevertheless, if temperatures remain normal, the current delay in crop development will translate into wetter grain at harvest. From research we conducted last year, we found that a deficit of 80 GDD at harvest could translate into about 2% more moisture in the grain for an adapted hybrid if fall temperatures are normal and harvest is planned for before November 1st.

Accumulated corn growing degree days (AGDDs) for selected locations in North Dakota for the period 1 May to 10 June, departures from normal for the same period, and typical daily GDDs for early June (data from NDAWN-


AGDDs 2007

Departure from Normal

Normal daily GDDs for early June





























Joel Ransom
Extension Agronomist for Cereal Crops

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