Gregory Endres, area extension specialist/cropping systems, Ezra Aberle, research specialist, and Dr. Robert Henson, research agronomist

NDSU Carrington Research Extension Center

This session consists of two parts: 1) An overview of a long-term cropping system study conducted by North Dakota State University at Carrington, and 2) Farm panel reports by Barry Fraser - Brandon, MB, Jim Nevin - Rapid City, MB, and Jerry Blotter - Coleharbor, ND, on their cropping systems management and results.

The long-term study has been conducted since 1987 to explore the impact of three crop rotations, three tillage systems and several nitrogen (N) treatments on numerous factors including crop seed yield and quality, pest management, and soil chemical and physical properties. The database generated is being used to provide support for recommendations for crop production and soil management.

The dryland field study was initiated in 1987 on approximately 60 acres of a Heimdahl loam soil at the NDSU Carrington Research Extension Center. Three rotations, with four crops in each rotation, were managed during 1987 to 2002. Whole plots consist of crops and subplots include combinations of three tillage and four N fertility treatments. Whole plot dimensions are 300 by 180 ft and subplot dimensions are 100 by 60 ft. Experimental design is a randomized complete block with a split-plot arrangement and three replications.

A ‘traditional’ rotation of hard red spring (HRS) wheat/sunflower/barley/fallow has been consistent during the 16 years of the study. The second rotation, ‘alternating grass/broadleaf’, has had changes in crop content during the study. During the fourth four-year cycle (1999 to 2002), the rotation included HRS wheat/soybean/durum/field pea. The third rotation has varied among four-year cycles. During the first three cycles, the rotation was ‘low input’ and consisted of HRS wheat/buckwheat-sweet clover/sweet clover/winter rye. During 1999 to 2002, this third rotation was dramatically revised to investigate new trends in crop sequences. This ‘two-year grass/two-year broadleaf’ rotation was HRS wheat/corn/soybean/canola.

The three tillage treatments include conventional, minimum and no-till. The targeted crop residue levels on the soil surface after crop planting for the three tillage systems include: conventional = <30%, minimum = 30 to 80%, and no-till = >80%.

N fertilizer treatments include the following: low = 30 lb/acre (1987 to 1990) or none (1991 to 2002), medium = 60 lb/acre (1987 to 1990) or 40 lb/acre (1991 to 2002), high 90 lb/acre (1987 to 1990) or 80 lb/acre (1991 to 2002), and composted manure = applied first year of four-year cycle at low to medium fertilizer N rate. N fertilizer source was spring-applied ammonium nitrate (34-0-0). N fertilizer generally was not applied to fallow or legumes.

Crops were established with commercial field equipment. Representative areas of plots were sampled by hand or research equipment for data collection.

The study is ‘data rich’ because of years of work and number of crops, crop sequences, tillage and N treatments, and numerous crop and soil parameters measured. Practical questions that potentially can be addressed with study results include:

*Crop response based on previous crop type and species.

*Impact of tillage system on crop performance during variable production seasons (e.g. low or high rainfall).

*Impact with crops, tillage systems and N treatments on soil nutrient status and quality.

*Crop and soil response to the application of manure versus commercial N fertilizer.

*Crop pest trends with tillage and N fertility treatments, and different broadleaf/grass crop sequence combinations

*Economic benefits of the tillage and N fertility treatments on crops and crop sequences.

Following are examples of information derived from the study:

*Fallow, a grain legume (soybean or field pea), or a grass (barley or rye) proceeded HRS wheat in all three rotations during 1987 to 1998. Averaged across years, rotations, and N treatments, HRS wheat seed yield in no-till was 31.7 bu/acre compared to 29.2 bu/acre with the other tillage systems. However, seed protein was slightly lower with no-till.

*Composted cattle manure was spring-applied at 10 tons/acre in 1995. During 1995, HRS wheat yield with the manure treatment was similar to medium and high N fertilizer treatments. However, in 1996 wheat yield was higher with the previous year manure treatment compared to the annual medium and high N fertilizer treatments.

*Barley yield averaged during 1988 to 1997 improved as N fertility rates increased under all tillage systems. However, no-till yield (49.6 bu/acre) was 5 bu/acre higher than the other tillage systems.

Additional study results will be included in the workshop presentation to stimulate thought and discussion on the impact of crop rotations, tillage systems, and fertility in cropping systems.