Sustainable Alfalfa Production on Coastal Plain Soils of the United States

Abstract

Alfalfa (Medicago sativa L.) is rarely grown on the Coastal Plain of southern United States. Production problems include infertile acid soils, inadequate pest control, and high humidity with frequent rainfall events that preclude adequate alfalfa hay drying conditions in spring. Research to overcome soil fertility problems included evaluation of nitrogen (N) rates over alfalfa row spacings and limestone and boron rates in split plot studies; phosphorus (P) rates using a randomized complete block design on eight soil series; and potassium (K), magnesium (Mg), and sulfur (S) rates and zinc (Zn), copper (Cu), and molybdenum (Mo) rates in central composite, rotatable design studies. Field-scale demonstrations were conducted to verify data from small plot research. Results indicate little need for N fertilization of alfalfa on Coastal Plain soils except possibly under cool or dry surface soil conditions. Increasing the between-row planting distance from 23 to 69 cm lowered alfalfa dry matter yield by 2.1 Mg ha 21 the seedling year. Alfalfa yielded 11 Mg ha 21 at all row spacings in the drought-affected third year. Dry matter yield was maximized at 49 -73 kg applied P ha 21 on soils testing below 19 mg P kg 21 by the NH 4 OAc-EDTA extraction method. The alfalfa stand was lost after one season on plots not fertilized with K. Applied Mg, S, Zn, Mo, and Cu had no significant effect on alfalfa yield. Dry matter increased .5 Mg ha 21 as pH was increased from 6.0 to 7.5. Boron applied at 3.4 kg ha 21 increased alfalfa yields 3.9 Mg ha 21 . With improved methods for site selection and adequate fertility, sustainable economic production of alfalfa is possible with rain-fed conditions on selected, limed Coastal Plain soils.

Impact of poultry litter application on alfalfa grown in Mississippi

“…Forage mass increased by 1,944 lb acre −1 to the 3‐yr mean for every 10‐inch increase in depth of a phytotoxic level of Al. With medium to high P levels present at our test site prior to fertilizer treatment application, our results validate those of Haby and Leonard (2005) in that other factors besides surface (<6 inches) nutrient availability contributed to stand decline and reduced FM in 2019. Though Al phytotoxicity was not measured in our study, highly weathered acid soils are prone to subsoil Al toxicity, even when surface pH is optimal; this was likely to have been a cause of diminished FM and PER in this field trial.…”

“…Establishment year alfalfa FM in lighter Coastal Plain soils has shown varying responses to applied N, P, and K. Applied N significantly increased alfalfa FM for specific harvests conducted in east Texas. In Haby and Leonard's (2005) study, no significant yield differences were observed when N was applied at rates greater than 25 lb N acre −1 per harvest. In our field trial, N was applied at rates of 140 lb N acre −1 yr –1 for Treatments 1 and 3, and 280 lb N acre −1 yr –1 for Treatment 2.…”

“…Of eight coarse‐textured soils tested in east Texas, only one alfalfa field trial responded to applied triple superphosphate in the first season of production (Haby & Leonard, 2005), even though several of the trial sites had low levels of soil test P. Their results indicate the poor relationship of soil test P to alfalfa yield response to fertilizer P. Contrastingly, application of P fertilizer increased total yield on a silty clay loam soil in northwestern Indiana that had low concentrations of extractable P (Berg et al., 2005). However, soil properties other than the supply of plant‐available nutrients may control alfalfa's response to P fertilizer (Haby & Leonard, 2005). Regression of alfalfa yield to the depth of phytotoxic Al concentrations in the subsoil accounted for 57% of FM variation on limed soils in east Texas.…”

“…(2020) did not observe any aboveground plant responses to K fertilization beyond an untreated control. Haby and Leonard (2005) reported stand thinning and eventual loss of stand in alfalfa plots that did not receive any fertilizer K in east Texas. Burmester, Mullins, and Ball (1991) reported that the greatest FM attained from plot trials on two Ultisols in the Coastal Plain were fertilized with 430 lb K acre −1 annually.…”

Boron Deficiency in Soils and Crops: A Review

“…Field-scale demonstrations have shown a considerable increase in alfalfa forage yields (3.9 Mg ha -1 or 159%) with B application. The sustainable economic production is possible under rainfed conditions on selected, limed Coastal Plain soils of US with improved methods of site selection, adequate fertility and management guidelines (Haby & Leonard, 2000.…”