Established Alfalfa Stands Research Articles

Application of Manure to Established Stands of Alfalfa and Alfalfa-Grass

Nutrient management plans require that manure application to corn and forage grasses be limited to crop N needs. This increases the likelihood that manure will need to be applied to other cropland such as alfalfa fields. In this review we summarize scientific literature on the potential agronomic and environmental impacts of manure application to alfalfa and mixed alfalfa-grass stands.

Weed Invasion in Established Alfalfa (Medicago sativa) Seeded with Perennial Forage Grasses

Component yields and forage quality were evaluated in established stands of alfalfa seeded alone and in binary mixtures with smooth bromegrass, orchardgrass, or timothy. Forage yields and quality were determined at three annual harvests in the third and fourth years after seeding. Weed yields in alfalfa seeded alone were significantly greater than those in the alfalfa–orchardgrass mixture. Average weed content was 24, 17, 2, and 15% for the alfalfa seeded alone, alfalfa–bromegrass, alfalfa–orchardgrass, and alfalfa–timothy, respectively. Seeding alfalfa with orchardgrass increased first harvest and annual forage yields while reducing alfalfa yield. Yields of orchardgrass often exceeded those of bromegrass or timothy. In the first harvest each year, crude protein was reduced and acid detergent fiber and neutral detergent fiber increased by including orchardgrass. Neutral detergent fiber was greater in alfalfa–orchardgrass than in the alfalfa seeded alone at most harvests. There were no consistent differences among the alfalfa seeded alone and the other mixtures in yield or quality.

Effect of fertilizer placement on yield of established alfalfa stands

Alfalfa yield response to P and K fertilization management has been documented elsewhere, but little work has been done in western Canada. Field studies conducted on two Manitoba soils for 4 yr evaluated the effects of four levels of monoammonium phosphate and three levels of potassium chloride fertilizers, applied as a surface broadcast or as an in-soil band application, on the yield of established alfalfa (Medicago sativa L.) stands. Applied P increased total annual forage yield on the clay loam soil by 1.53 t h−1 (47%), when averaged over the 4 yr of the study, but did not increase yields on the fine sandy loam. Yield response to P application on the clay loam soil increased over the 4 yr of the study. Potassium application resulted in minor or no increases in forage yield on both soils. On the clay loam soil, there was no yield difference between banded and broadcast fertilizer applications. On the fine sandy loam soil, band application reduced yields slightly compared with broadcast application, particularly at the first harvest following fertilizer application. Grass ingress into the plots was reduced by K application but was not affected by P fertilization, which may indicate a beneficial effect of K fertilization on alfalfa vigor and persistence. Key words: Potassium, phosphorus, banding, broadcast, persistence

Abundance of the Garden Fleahopper (Hemiptera: Miridae) on Alfalfa and Parasitism by Leiophron uniformis (Gahan) (Hymenoptera: Braconidae)

In 1985, the garden fleahopper, Halticus bractatus (Say), was observed damaging alfalfa regrowth in New Jersey. Field observations during the next two years showed that this insect was sporadically abundant but that it usually did not cause noticeable injury to established alfalfa stands. The parasite Leiophron uniformis (Gahan), the first nymphal parasite discovered in this host, was detected in these collections. In addition, a small proportion of garden fleahopper adults was parasitized by this braconid and by an unidentified nematode. L. uniformis killed an average of 50% of all fleahopper nymphs that we sampled and is likely the principal reason why populations of this pest are not larger and more damaging in alfalfa.

Comparison of Fall-Applied Pronamide with Spring-Applied Sethoxydim for Quackgrass (Agropyron repens) Control in Established Alfalfa (Medicago sativa)

Established stands of alfalfa (Medicago sativaL.) at two field locations were treated at one date in the fall with pronamide [3,5-dichloro (N-1,1-dimethyl-2-propynil) benzamide] at 0.8 and 1.6 kg ai/ha and at two dates in the spring with sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} at 0.3 and 0.6 kg ai/ha for the control of quackgrass [Agropyron repens(L.) Beauv. # AGRRE]. Herbicide efficacy was compared by measuring botanical and chemical composition and yield of forage. Both chemicals suppressed quackgrass in first-cutting herbage. While sethoxydim at the higher rate was equivalent to pronamide for increasing the proportion of alfalfa in forage, pronamide was superior for increasing seasonal total yield. Late postemergence applications of sethoxydim were more effective for quackgrass regrowth control than earlier spring applications. Controlling quackgrass in late spring resulted in lower crude protein (CP) content in first-cutting forage than did controlling it in fall. Alfalfa competing with untreated quackgrass had a lower CP content than where quackgrass was controlled with herbicides. All herbicide treatments reduced the neutral-detergent fiber (NDF) of the herbage. As measured by the acid-detergent fiber (ADF) concentration of alfalfa, sethoxydim slightly retarded spring growth of the legume.

Sulfur fertilization of two aquic hapludalf soils: I. Effect on alfalfa yield and quality

Abstract Alfalfa is rapidly increasing as a cash forage crop on the more arable soils in south central Missouri. These soils are natively acid and low in fertility having formed from loamy, sandy and cherty alluvium found in the bottom land areas, under forest vegetation with native grasses in the open areas. The two experimental sites selected were recently established alfalfa stands, Site I was under irrigation and Site II nonirrigated. Two S materials (SO4‐S and elemental S) at rates of 0, 34 and 68 kg S ha‐1 in 4 replications were applied. Yields, plant S, crude protein and IVDMD were measured for individual harvests in 1980 and 1981. Alfalfa yields were not increased at both locations with S fertilization. Forage S content was significantly increased and the N/S ratio significantly decreased on the higher yielding irrigated alfalfa, but not with the nonirrigated alfalfa. Forage S levels of 0.19% S and N/S ratio of 17.9 during dry year did not result in yield increase when S fertilized. There was obse...

Rhizobium meliloti distribution in the soil following alfalfa inoculation

Alfalfa seeds, inoculated with an antibiotic-resistantRhizobium meliloti strain, were planted in three replicated field plots at Clayton, N.C. Core samples were taken three times in the next year at 0, 10, and 20 cm from the edge of each plot. Soil subsamples were taken from within each core sample at 0, 6, 12, and 18 cm depths. The numbers of the inoculum Rhizobium strain in each soil subsample were determined by inoculation of alfalfa plants with diluted soil samples. In general the distribution of rhizobia showed some movement outward and downward in the soil. Lower counts were obtained at the surface during summer. The Rhizobium persistence pattern in the soil differed in the three plots which is consistent with the variability in Rhizobium numbers often observed in established alfalfa stands.

Weeds and Alfalfa Hay Quality

Established stands of alfalfa (Medicago sativa L. ‘Lahontan’) at six field locations were treated with soil-active herbicides during the dormant period for the control of winter annual weeds. Weeds and alfalfa were hand separated at the first harvest. This forage, which varied widely in weed content, was analyzed for protein. The percentage of protein correlated negatively with weed content in all cases. Analyses of covariance revealed that the direct effect of the herbicides on protein content was either small or absent and that the primary cause of the negative correlations was weed content.

Vertical Distribution of Soil Phosphorus and Potassium on Several Established Alfalfa Stands That Received Various Rates of Annual Fertilization

AbstractAvailable soil phosphorus, available soil potassium, calcium, magnesium, and pH were determined at various depths on four soil profiles under established stands of alfalfa. Three experiments were set up in a complete factorial design using four rates of annual phosphate application and five rates of annual potash application. The fourth experiment received five annual applications of potassium and no applications of phosphate since it was on soil inherently high in phosphate.Available potassium after 4 years of annual applications of potash on three soils and 5 years on one soil was concentrated in the 0‐ to 6‐inch layer. Only a slight movement of potassium into depths below 6 inches was noted even at high rates of annual potash fertilization. Available soil phosphorus was found to be concentrated in the 0‐ to 3‐inch layer. It was found that annual potash and phosphate applications had little effect on soil reaction.Significant difference in yield at the 0.05 level of probability was found between the 0‐ and the 100‐pound‐peracre annual potash treatment in each experiment, and between the 0‐ and the 60‐pound‐per‐acre annual phosphate treatment on those experiments receiving phosphate fertilization. No significant response to higher rates of annual todressing was obtained.Yield data were correlated with soil test potassium values of various soil layers. A poor correlation was found to exist between soil test potassium values and yield. Correlation values were increased by addition of phosphorus soil test values into the equation.

Nitrogen Applications to New and Established Stands of Alfalfa1

Nitrogen Applications to New and Established Stands of Alfalfa¹

Effect of Adding Commercial Inoculant to Established Stands of Alfalfa

Effect of Adding Commercial Inoculant to Established Stands of Alfalfa

Granulated Systemic Insecticides on Established Stands of Alfalfa for Control of the Spotted Alfalfa Aphid1

The application of the systemic insecticides, Bayer 19639, Thimet and Am. Cyanamid 12008, on established stands of alfalfa was tested in granulated form for protection against the spotted alfalfa aphid, Therioaphis maculata (Buckton). Bayer 19639 at 1 pound of the active ingredient per acre was more effective than Thimet at the same rate during the “explosive” and relatively static high point of the infestation. Both materials were effective during the waning period of the population cycle in reducing the numbers of aphids to a non-economic level. Am. Cyanamid 12008 was ineffective in controlling the spotted alfalfa aphid when applied in a granulated form to established stands.