Document Actions

Inoculant use in Modified Relay Intercropping

Last modified 2007-11-16 14:17

Evaluation of USDA Inoculant in a Modified Relay Intercropping System

Objectives:

1.To evaluate the effect of a new USDA soybean inoculant on soybean yield in a modified relay intercropping system.
2. To measure wheat yield in a Modified Relay Intercropping system.

Field Notes

Location of Test:	D. Brewer farm Crawford County
Soil Type:	Blount,Pewamo
Drainage:	Systematic & non-systematic
Tillage:	no-till
Previous crop before wheat:	Soybeans
Average Plot Soil Test Values at Brewer Farm:	pH - 6.9 P - 31 ppm K - 122 ppm
Fertilizer at Brewer Farm:	Applied Fall 1200, 21-75-75, 85 lbs/ac nitrogen applied in spring
Herbicide in 2000:	2,4-D ester @1.5 pt/ac applied @ Feeke's GS 6.5
Soybean Varieties	Pioneer 9306
Soybean Seeding Rate:	90 lbs/acre (3000 seeds/lb)
Wheat & Soybean Planting Dates:	10/1/1999 & 6/12/200
Wheat harvest Date:	7/5/2000
Design:	Completely randomized

Materials and Methods

To address the issues of farm profitability and environmental protection, a modified relay intercropping (MRI) system has been studied. In this system, soybeans are planted into wheat at or past the heading stage of growth. A modified relay intercropping system can effectively utilize farm labor, time and equipment, while at the same time increasing farm net profit.

A Great Plains 15' drill was used to plant all wheat and soybeans with wheat. A 20" tram line was established to guide the planting of soybeans into wheat. Contact the author for details on the MRI system.

New soybean inoculants have been reported to give a positive yield response in conventional tillage soybeans. As such, USDA inoculant at the labeled rate was mixed well into soybean seed and soybeans were immediately interseeded into wheat on 6/12/2000. Soils were moist at time of planting.

A completely randomized design was used with four replications of two treatments - USDA inoculant and untreated soybeans. Plots size per treatment was 0.138 acres. A 15-foot Great Plains 1500 drill was used to plant both the wheat and soybeans in 10-inch rows. A 20-inch tramline was established in the wheat to facilitate soybean planting into wheat.

Results

Treatments	Yield (bu/A)
Control	37.2
USDA Inoculant	37.1
Significance	NS

Summary

There were no significant yield differences between the soybeans inoculated with USDA inoculant and soybeans without inoculant in the modified relay intercropping system.

We now have six years of replicated research on the Modified Relay Intercrop system. Overall the data are encouraging. However, soybean yields fell dramatically from a 33 bu/acre average over the previous 4 years, to 5 bu/acre in 1999. These low yields can be attributed to both a very low total summer rainfall and poor rainfall distribution. Essentially no rain fell after August 13 at the plots. The total rainfall from June 1 to August 30 was 5 inches. MRI soybeans are delayed in maturity and thus require rainfall later in the season to finish development. Rainfall appears to follow a normal distribution. Thus about every 5 years, it would be expected to have a very dry year, and thus poor soybean yields in the MRI system.

Finally, when looking at gross revenue generated, the MRI system has been very favorable when compared to single crops of either 80 bushel wheat or 55 bushel soybeans. Using $3.00 wheat and $6.00 soybeans, the 6-year average of the MRI system averaged $399 gross revenue per acre. Eighty bushel wheat would generate $240 per acre (no straw sales) and 55 bushel soybeans would calculate to $330 per acre. A 160 bushel per acre corn crop at $2.40 per bushel would generate $384 per acre.

Sections