Measuring the Value of Inter-Seeding Legumes into Established Cool Season Pastures in North Central Kansas – Part 2

2010 Annual Report for FNC09-753

Project Type: Farmer/Rancher
Funds awarded in 2009: $6,000.00
Projected End Date: 12/31/2011
Region: North Central
State: Kansas
Project Coordinator:
Calvin Adams
Adams Ranch

Measuring the Value of Inter-Seeding Legumes into Established Cool Season Pastures in North Central Kansas – Part 2

Summary

WORK ACTIVITIES
In 2009 and 2010, at each species, landscape, and nitrogen combination, stands were evaluated in June and September using two large 40-inch by 40-inch frequency frames. Each large frame was divided into 100 smaller 4-inch by 4-inch subsquares. Each sub-square that contained a new rooted legume seedling was counted, so a frequency score of 100 percent indicated that all small squares of a large frame contained a legume seedling. A total of eight large frames were counted in each treatment combination on each date. In 2010, the year after legume seedling establishment, stands also were hand harvested for yield just prior to each of three grazing occupancy dates.

RESULTS AND DISCUSSION
A frequency of at least 21 percent was set as the criterion for successful establishment. By dividing the frequency percentage by 10.76 (the number of square feet within the frequency frame), a conservative density estimate of established legumes per square foot can be calculated. Successful establishment with 21 percent frequency subsequently translates into a plant density of at least 2 plants per square foot, because more than one seedling was present within some of the subsquares that were counted.

Examination of the data reveals a number of important and interesting findings. First and foremost, some legumes had consistently greater establishment at each of the nitrogen fertilizer and landscape position combinations (Table 1 and Table 2). Legumes that showed acceptable overall establishment at both landscape positions were Korean lespedeza, yellow-flowered alfalfa (falcata), and purple-flowered alfalfa (sativa). However, establishment on the upland site was greater than on the lowland site for these legumes (Table 1). Yellow sweetclover established successfully on the upland site in 2009, but frequency was reduced in 2010. The remaining legumes did not establish consistently well at either landscape position. Averaged over all legume species, upland sites had approximately 40 percent greater legume establishment than lowland sites.

Fertilization also affected stand establishment. Legumes that showed acceptable overall establishment with or without added N fertilizer were Korean lespedeza, yellow-flowered alfalfa (falcata), and purple-flowered alfalfa (sativa; Table 2). However, establishment was greater for these legumes and for yellow sweetclover and white clover on sites without added N fertilizer in both 2009 and 2010. Averaged over all legume species, unfertilized sites had 44 percent greater establishment than fertilized sites.

Stands improved over the first growing season for some legumes (Table 3). Frequency counts in September 2009 were consistently higher than the June counts for both alfalfas and yellow sweetclover. In 2010, yellow sweetclover frequency was lower in the fall than in the spring.

Lowland sites in general had greater yield in 2010 than upland sites (Table 4). Fertilization with 40 lb N per acre did not increase season forage yield. However, on upland sites, unfertilized areas with purple alfalfa and yellow alfalfa had greater yield than fertilized areas. Purple- and yellow-flowered alfalfa on the unfertilized uplands also had greater yield than the grass-only control sites. On lowland sites that were fertilized, purple and yellow alfalfa also had greater yield than the grass-only control.

Each of the established legumes offers unique opportunities and challenges. The two alfalfas, as perennials, offer the possibility of long-term survival and production without having to worry about frequent re-seeding. The biennial yellow sweetclover may present a long-term maintenance problem depending on timing of grazing. Pasture rest during flowering and seed set should allow natural reseeding to occur. Yellow sweetclover had completed its life cycle and seed set by late summer 2010. New seedlings had not germinated from the biennial species by the September sampling period, and thus it had a low frequency in the fall of 2010. New biennial sweetclover seedlings may appear in spring of 2011, but likely will not contribute much to spring forage yield. Korean lespedeza, a summer annual, may present a problem with maintenance and reseeding at northern locations. It is a major component in most cool-season pastures in southeast Kansas, and it did set seed in 2009 to successfully reestablish itself in 2010. As long as grazing management allows rest or plants are allowed to flower and set seed without heavy defoliation, Korean lespedeza most likely will produce seed annually, or at least periodically, to maintain stands indefinitely. However, the lespedeza appeared to contribute little to the overall yield of the pastures even though plant frequency values were well above 21 percent. Of the four legumes with the most successful establishment, purple alfalfa and yellow alfalfa on the upland unfertilized and lowland fertilized sites showed the greatest potential to increase forage yield.

Implications: Adding legumes to smooth bromegrass pasture could reduce the amount of commercial fertilizer needed to attain optimal forage production. Furthermore, adding legumes to brome pasture could extend the brome grazing season by increasing the quantity and quality of forage produced in mid-summer, and could improve animal weight gain and profitability potential. Purple-flowered alfalfa and yellow-flowered alfalfa no-till seeded into smooth bromegrass pasture established at acceptable plant densities of more than 2 plants per square foot. Both alfalfa types provided increased forage quantity above that of fertilized or unfertilized smooth bromegrass pasture. At current approximate cost of $53.00 per acre to seed the purple-flowered alfalfa, $67.00 per acre to seed the yellow-flowered alfalfa, and $27.80 per acre to apply 40 lb N per acre, savings in N fertilizer application alone could pay for alfalfa seeding in two to three growing seasons. Purple- and yellow-flowered alfalfas seeded into smooth bromegrass pasture have potential to contribute to greater season forage quantity and quality within two years of seeding.

[Editor’s Note: To see properly formatted versions of the tables, see the attached PDF version of the report.]

Table 1. Average frequency (number of 4-inch by 4-inch subsquares) having at least one desired (target) legume rooted within it at each landscape position in 2009 and 2010. Values are averaged across both fertilized and unfertilized plots, and averaged across both spring and fall sampling

2009, 2010
Plant, Upland, Lowland, Upland, Lowland
—————–Frequency (percent)————-
Birdsfoot trefoil, 6, 3, 1, 1,
Cicer milkvetch, 7, 3, 6, 4,
Hairy vetch, 3, 3, 0, 0,
Korean lespedeza, 80, 76, 58, 39,
Purple alfalfa, 48, 23, 55, 33,
Yellow sweetclover, 30, 15, 13, 7,
White clover, 13, 14, 10, 19,
Yellow alfalfa, 48, 31, 56, 35,
LSD1 0.05, 7
Average, 29, 21, 25, 17,

1 LSD0.05 = Least significant difference. Values compared within rows or columns that differ by more than the LSD value are statistically different.

Table 2. Average frequency (number of 4-inch by 4-inch subsquares) having at least one desired (target) legume rooted within it at each fertilization level in 2009 and 2010. Values are averaged across both upland and lowland plots, and averaged across both spring and fall sampling

2009, 2010
Plant, 40 lb per acre N, 0 lb per acre N, 40 lb per acre N, 0 lb per acre N,
—————–Frequency (percent)—————
Birdsfoot trefoil, 5, 5, 1, 1 ,
Cicer milkvetch, 5, 5, 4, 6,
Hairy vetch, 3, 3, 0, 0,
Korean lespedeza, 71, 85, 37, 60,
Purple alfalfa, 29, 43, 28, 61,
Yellow sweetclover, 13, 32, 4, 16,
White clover, 5, 23, 3, 26,
Yellow alfalfa, 31, 48, 26, 65,
LSD1 0.05, 7
Average, 20, 30, 13, 29,

1 LSD0.05 = Least significant difference. Values compared within rows or columns that differ by more than the LSD value are statistically different.

Table 3. Average frequency (number of 4-inch by 4-inch subsquares) having at least one desired (target) legume rooted within it at each spring or fall sample period in 2009 and 2010. Values are averaged across both upland and lowland plots, and averaged across both fertilized and unfertilized sites.

2009, 2010
Plant, Spring, Fall, Spring, Fall
—————–Frequency ( percent)————
Birdsfoot trefoil, 8, 1, 1, 1
Cicer milkvetch, 7, 3, 9, 2
Hairy vetch, 5, 0, 0, 0
Korean lespedeza, 77, 79, 49, 48
Purple alfalfa, 29, 42, 45, 44
Yellow sweetclover, 17, 28, 20, 0
White clover, 16, 12, 16, 13
Yellow alfalfa, 34, 45, 43, 48
LSD1 0.05, 8
Average, 24, 26, 23, 19

1 LSD0.05 = Least significant difference. Values compared within rows or columns that differ by more than the LSD value are statistically different.

Table 4: Average total yield (lb per acre) of legume-bromegrass mixtures at two landscape positions and two N fertilizer levels one year following legume interseeding. Yields are the sum of two spring harvests and one fall harvest in 2010. Due to poor establishment, trefoil, milkvetch, and hairy vetch plots were similar to the grass-only control and were not harvested.

Lowland, Upland
Plant, 40 lb per acre N, 0 lb per acre N, 40 lb per acre N, 0 lb per acre N
——————-Yield (lb per acre)—————
Grass-only control, 5173, 4784, 2893, 2688,
Korean lespedeza, 6067, 5059, 3384, 2740,
Purple alfalfa, 7524, 6456, 3124, 5348,
Yellow sweetclover, 5781, 5523, 3931, 3739,
White clover, 5667, 5357, 2938, 1927,
Yellow alfalfa, 7824, 4776, 3007, 4864,
LSD1 0.05, 1552
Average, 6339, 5326, 3213, 3551,

1LSD0.05 = Least significant difference. Values compared within rows or columns that differ by more than the LSD value are statistically different.

WORK PLAN FOR 2011
We will continue to do what has been described in our proposal.

OUTREACH
We were scheduled to present our results at the Kansas Hay and Forage Conference but the conference was canceled at the last minute. We plan to present the results at the 2012 Kansas Hay and Forage Conference. We will also do additional outreach next year as described in our proposal including the farm tour, poster presentations, and professional journal article.