Alfalfa and corn response to sulfur fertilization on three Pennsylvania soils

Abstract

Sulfur deficiencies have become more widespread throughout the United States as a result of: (a) reduced SO₂ emissions, (b) the use of high analysis fertilizers that contain less S, and (c) reduced applications of animal waste on cropland. The S status of Pennsylvania soils is not known.

Studies were conducted at three locations in Pennsylvania under different soil and climatic conditions to determine crop response to S applications. The experimental sites were on a Hagerstown silt loam (Typic Hapludalf), a Gilpin channery silt loam (Typic Hapludult), and a Morrison sandy loam (Ultic Hapludalf) at Landisville, Rector, and Zion, Pa., respectively. Two S materials, elemental S and fluidized bed combustion waste material (FBM), were applied annually to alfalfa and corn at three rates of application: 34, 67, and 134 kg S/ha, with appropriate controls. Elemental S plus CaO treatment was applied to alfalfa at the same three rates. Two levels of N were used in the corn trials, 112 and 224 kg N/ha. The experimental design was a randomized complete block, replicated four times.

The nutritive value of alfalfa was improved in terms of higher S concentrations and lower N:S ratios by S fertilization, but nutritive value of corn grain and silage was unaltered. Sulfur concentration in alfalfa was increased and the N:S ratio decreased approximately 9% by an application of 134 kg S/ha (mean over three years and three locations). The reduced ratios were closer to the optimum N:S ratio (10 to 13.5:1) suggested by animal nutritionists for ruminants. Protein content and dry matter digestibility (IVDMD) of both crops were not altered by S fertilization.

There generally were no significant differences between S sources. Fluidized bed combustion waste material (FBM), in addition to being an effective source of S, had the benefit of containing 33% CaO.

Alfalfa yields were not significantly increased by S fertilization until the third year at two locations (Landisvilie and Zion). In the third year, S fertilization increased yields up to 14% at Landisville. Yields were lower at Rector and were not increased by S fertilization. Yields of corn grain and silage were not improved by S fertilization, nor was there a S X N interaction.

Under similar soils and weather conditions of this study, only the most intensive management systems (yields over 11.2 MT/ha (5 tons/acre)) are likely to tax residual levels of S and benefit from applications of S.

Key words:

• alfalfa
• corn
• sulfur
• fertilizer