Tallgrass prairies are an important source of hay and summer forage in the Great Plains. A study was conducted in 1989 and 1990 on two excellent condition tallgrass prairies in eastern Nebraska to determine if the production and forage quality of big bluestem (Andropogon gerardii var gerardii Vitman), the dominant warm-season grass, could be manipulated by burning on different dates in the spring and applying fertilizer. Vegetation was harvested at approximately 30-d intervals from mid-June to mid-August. Big bluestem was separated from the vegetation, weighed, analyzed for in vitro dry matter disappearance (IVDMD), crude protein concentration (CP), and neutral detergent fiber concentration (NDF). Early or mid-spring burning increased June forage production by at least 52%, and mid-or late-spring burning increased August forage production by at least 70% compared with no burning. In June 1989 and 1990, big bluestem IVDMD was greatest on areas burned in late spring. Late-spring burning increased CP in June by at least 15% when compared with all other burn treatments, and increased CP in July by 8% compared with early spring burning. Fertilization increased CP in June by 22% and in July by 23% and 17% in 1989 and 1990, respectively, when compared with nonfertilized big bluestem. Burning in early, mid-, or late spring 1989 decreased NDF in June and August when compared with no burning. The quantity and quality of big bluestem forage available during the summer can be improved by spring burning and fertilization. Research Question Durum wheat is a major crop in North Dakota. Farmers plant durum seed derived from widely varied sources. The primary objective of this study was to accumulate samples from farmers' drills to compare the quality of seed being planted and evaluate the field performance. Literature Summary Numerous studies have related the effect of seed viability and seed vigor to field performance. Seed size or test weight is another component of seed quality that has been studied extensively. Generally large seed with good viability has the best performance. Surveys have been conducted in several states to evaluate the quality of seed being planted. Frequently, these surveys have been used to bring attention to a continuing need for improved purity of seed being sold in commercial channels. No studies, however, have been published to associate the impact of seed quality on economic potential for durum wheat. Study Description Durum seed sources used by farmers were sampled at planting time in eight North Dakota counties during 1987 and 1988. Accumulated samples were analyzed for germination percentage and purity variables in the lab. Replicated field trials were conducted at two locations in the year following sampling to determine emergence, grain yield, and test weight performance. Applied Questions What is the quality of durum seed currently being planted? Overall quality of the seed samples from 274 drills was extremely variable. Germination tests averaged 84.5%, which is below the minimum standard for certified seed. Mean values for purity were excessive for other crops and weed seeds exceeded the maximum level for certified seed, but did not differ significantly from certified seed samples. Field emergence ranged from 26 to 100%. Stand had a significant effect on grain yield, particularly when the environment favored high yield potential (Fig. 1). How does certified seed compare with noncertified in yield performance? The survey indicated that 13.2% of the durum acreage was planted with certified seed. Grain yield from certified seed averaged 7.1070 higher than from noncertified seed. These data indicate the statewide average durum yield and economic return could be increased simply through the exclusive use of seed equivalent to certified seed. Cost inputs associated with additional weed control and possible reduced crop value due to seed impurity would add to the economic value of high quality seed. Figure 1Open in figure viewerPowerPoint Effect of plant stand on durum grain yield averaged over two locations.