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Long Term Tillage and Fertility Study at Carrington

County Agent News
Dan Folske
December 14, 2020

Long Term Tillage and Fertility Study at Carrington

In 1987, a long-term cropping systems study started at the NDSU Carrington Research Extension Center. This is the longest replicated cropping systems trial in North Dakota.

Three sets of 4-year crop rotations are replicated three times each year. The eighth cycle ended in 2018. The original crop rotation, maintained until 2003, was: Hard Red Spring Wheat/Sunflower/Barley/Fallow. At the beginning of the fifth cycle in 2003, this crop rotation was updated to replace Fallow with Soybean. The other two current crop rotations are: Hard Red Spring Wheat/Field Pea/Corn/Soybean, and Hard Red Winter Wheat/Corn/Soybean/Hard Red Spring Wheat. Each crop within each rotation is planted every year.

The fertilizer treatments are: (1) urea broadcast applied each spring to all plots, except field peas and soybeans, at 0, 50, 100, or 150 pounds of N per acre and (2) composted beef feedlot manure applied once at 200 pounds of N the first year of each cycle. These treatments are imposed in strips perpendicular to the three tillage systems: conventional, minimum tillage, and no till resulting in 15 sub-plots within each crop.

The conventional tillage system starts with disking to a depth of approximately three inches shortly after combining. This is followed by chisel plowing later in the fall prior to freeze up. In the spring, the ground is worked with a field cultivator prior to seeding or planting.

The current minimum tillage has become more of a rotational tillage system. It was changed to reflect current reduced tillage farming practices of the area. It is essentially not tilled except for the fall prior to the corn and sunflower rotations. That fall and the following spring it is worked just like the previously mentioned conventional tillage treatment.

The no-till treatment is just as it sounds: there is no tillage performed except what disturbance is created by the disk drill or planter. Instead of tillage, a chemical burn down with herbicides is performed in the fall for weed control after combining and again in the spring for weed control prior to seeding.

As you can see from the cycle eight table above there was no negative impact on grain yield when reducing tillage. Reduced tillage did statistically impact protein content of soybean (positively) and the wheat (negatively, yet not enough for a dockage at the elevator.)
Note: Composted manure sunflower plots were negatively impacted by preferential deer grazing most years.

As shown in this table, cycle eight yield tended to increase with increasing nitrogen rates. The composted manure treatment performed as well as comparable commercial fertilizer rates in the non-legume plots. The yield in field pea and soybeans were higher, possibly due to increased phosphorous and micronutrients allowing nitrogen fixation and nitrogen scavenging from higher organic matter mineralization. However, the protein content of the wheat crops was limited by the composted manure treatment, resulting in a significant price penalty at market. Soybean protein content was lower for the previous 0 & 50 pound rates, and as a result, oil content was higher. However, neither had a negative impact on price received at the elevator.

This information was provided by Ezra Aberle, Agronomy Research Specialist at the NDSU Carrington Research & Extension Center

Filed under: Burke news
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