Soybean Varieties for Organic Production in North Carolina

by: Dr. Phil Rzewnicki, NCSU Crop and Horticultural Science, Teaching Assistant Professor

Introduction

There is increasing interest among North Carolina crop producers to capture the profitability offered by the certified organic market. Demand for organic livestock feed grains is growing in the state particularly for feeding organic poultry. There is also increased interest in developing organic dairy and pork production. In the organic industry there is also a large demand overseas for food grade soybeans but farmers in our state have not yet considered which varieties to grow. Currently popular varieties in food soybean markets are of very short maturity. The fuller range of soybean maturity that is attainable under North Carolina growing conditions may support interest in other varieties.

Feed grade varieties grown in performance trials under conventional management may not perform similarly under organic production practices. For food grade varieties there are little or no performance reports avaialbe. The objective of this trial was to evaluate food grade and feed grade soybeans grown under organic management conditions.

Method

The soybean varieties in this trial were grown on land dedicated to organic management at the Center for Environmental Farming Systems on the Cherry Research Farm in Goldsboro . Feed grade varieties currently used by North Carolina organic producers, some organically produced food grade seed, a food grade variety popular in the organic industry, non-GMO feed grade varieties that performed well under conventional management in recent NC State University trials, and a food grade variety not yet avaiable on the market were grown in replicated variety performance strips. Nine food grade and 5 feed grade varieties were evaluated for early growth vigor, crop canopy development, grain quality, standability and yield.

Food grade varieties, maturity groups and the sources of the seed were:

Vinton 81, Group I, Albert Lea Seed in Minnesota

NC+ 36YP6, Group III, Blue River Organics in Nebraska

Ohio FG4, late Group III, Ohio Foundation Seeds

Ohio FG5, Group IV, Ohio Foundation Seeds

NC+ 41YP5, early Group IV, Blue River Organics in Nebraska

NC+ 43A7, Group IV, Blue River Organics in Nebraska

NC+ 52Y6, Group V, Blue River Organics in Nebraska

R1705, Group V, K&K Farm Service in Arkansas

N01-10974, Group VI, experimental from Tommy Carter, USDA-ARS at NC State

Feed grade varieties and the sources of the seed were:

HBK 5894, Group V, Hornbeck Seed in Arkansas

Hutcheson, Group V, Earl York & Son in North Carolina

USG 5002T, Group V, UniSouth Genetics in Tennessee

NC Roy, Group VI, North Carolina Foundation Seed

NC Raleigh Group, Group VIII, North Carolina Foundation Seed

Cook Group, Group VIII, Georgia Certified Seed

Target planting rate was calculated to achieve 7 to 8 plants per foot of row (120,000 to 140,000 germinated seeds per acre) adjusting for seed weights and germination rates.

The test site soil type consists primarily of Wickham sandy loam. The previous crop was annual small grain grown as a cover crop and rolled for ground cover before grain heading occurred. Prior to soybean planting, lime was applied at 1400 lb/ac on April 22 and 60% potash was applied at a rate of 200 lb/ac on April 29. The soybeans were inoculated prior to planting with Nitragin (Optimize) at a rate 4.25 ounces per 100 lb of seed. The cultivars were planted with a 4-row planter on May 24 in 30" rows with four replications in a randomized complete block design. Each variety strip was 8 rows wide and approximately 200 feet in length. The food grade varieties and feed grade varieties were planted as separate groups within each replication. Weed control was two passes of a row cultivator with sweeps between the rows when the soybeans were 3 to 4 inches tall and again when they were about 12 inches tall.

Results and Discussion

Soybean growth was observed weekly in one replication from five to twelve weeks after planting. By the eighth week canopy closer was achieved in six varieties (NC+36YP6, Ohio FG4, Ohio FG5, Hutcheson, NC Raleigh and Cook). By the twelfth week after planting, all the varieties in the trial had closed canopies and with the exception of three feed grade varieties had set pods. The only sign of plant disease observed was a slight infestation of frogeye leaf spot on all four entries from Blue River Organics. Insect damage was moderate across the feed grain varieties by corn earworm but this was confined to a single replication.

Lack of precipitation in the 2005 growing season was a major factor in reducing soybean yields in this trial. The first hard freeze occurred November 11, 2005. From planting until this date, only 16.8 inches of precipitation occurred at the Cherry Research Farm where the trial was located. For the same time period, normal annual precipitation at Goldsboro has a 30-year (1970-2000) average of 21.9 inches. This rainfall deficit severely reduced yields as reflected in Table 1.

Since the varieties span a wide range of maturity groups, harvest occurred on three different dates. The first harvest date was October 7 and included Groups I and III. The second harvest date was October 19 and included Groups IV and V. Cool, moist climate after the first hard freeze slowed moisture dry down of beans that had developed in remaining pods and it was not until December 14 that the remaining varieties were harvested. The center six rows of each variety strip were combined in three of the four replications. Excessive weed growth in one replication prevented machine harvesting until all weed material had matured and dried down adequately. In this replicate, yield determination was done by hand harvest sampling at the same time as the other replications of each variety were mechanically combined.

Table 1. Yields
Food Grade	bu/ac
Ohio FG4	31.0 a
NC+ 43A7	27.9 ab
Ohio FG5	27.1 abc
NC+ 36YP6	25.3 abc
NC+ 41YP5	23.6 bcd
NC+ 52Y6	20.5 cd
Vinton 81	20.2 cd
R1705	16.4 de
N01-10974	12.3 e
lsd (.05)	7.2
Feed Grade
HBK 5894	18.5
Hutcheson	20.0
USG 5002T	26.3
NC Roy	21.8
NC Raleigh	22.2
Cook	19.9
	ns

Samples have been submitted on all varieties for protein and oil content analysis. Some tofu quality testing will be done on a few food grade samples for educational purposes. However, tofu quality comparisons among all the food grades may not be possible. According to ARS agronomist, Dr.Tommy Carter, many of the soybeans would not meet market acceptability standards due to the weathering exposure of the seeds. This was attributed to this season’s cool, humid conditions during late seed development. For food grade soybeans, as seed pods approach the R6 stage and seeds mature during R7 and R8, ideal conditions call for low humidity and harvesting within a few days. Minimizing exposure of full seed to adverse weather is key to preserving attractive seed coat and seed shape quality in the food grade market.

This project was supported in part by a grant from the North Carolina Crop Improvement Association. Assistance in preparation for the project was provided by Dr. Jim Dunphy in Crop Science.

 

 

 

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