Effects of Soil Calcium and pH on Seed Germination and Subsequent Growth of Large Crabgrass (Digitaria sanguinalis)

Abstract

Large crabgrass is a problem weed in horticultural crops, particularly in turfgrass in the southeastern United States. If growth of large crabgrass could be suppressed via soil pH or calcium levels, control of this weed in turfgrass might be improved while minimizing herbicide usage. To determine the effect of soil calcium and pH on germination and growth of large crabgrass, seeds were sown in a loamy sand soil amended with calcium carbonate (CaCO3) or magnesium carbonate (MgCO3) that established a range of soil pH from 4.8 to 7.8. Seeds were also sown in soil amended similarly with calcium sulfate (CaSO4), which does not affect pH, that established a range of exchangeable Ca levels corresponding to the Ca range in CaCO3from pH 4.8 to 7.8. Seed germination of large crabgrass was unaffected by pH when soil was amended with CaCO3, whereas seed germination decreased with increasing pH when soil was amended with MgCO3. Crabgrass germination was not affected by Ca (CaSO4) independent of pH changes. Increasing soil pH reduced shoot and root dry weights of seedlings regardless of material used to raise pH. Maximum shoot dry weights occurred at pH 4.8 in the unamended soil, whereas maximum root dry weights occurred at ranges from pH 5.8 to 6.3 for CaCO3and pH 5.3 to 5.8 for MgCO3. Shoot and root dry weights were not affected by Ca when soil was amended with CaSO4. By raising soil pH levels, the growth of large crabgrass and its ability to compete with turfgrass may be reduced. Raising exchangeable Ca does not appear to be an effective management tool for control of this weed species.

Soil pH Effects on the Shoot and Root Yield of Crabgrass

“…Buchanan and coworkers (3) also found that crabgrass was tolerant of low levels of soil pH. In contrast to the current study, Pierce et al (16) reported that shoot dry matter of crabgrass decreased as soil pH increased from 4.8 to 7.8. However, the rate of yield decrease was greatest at pH levels from 6.0 to 7.8, which were primarily outside of the range used in the current study.…”

“…Warm‐season grasses are, in general, tolerant of acidic soil conditions (18). Limited research and anecdotal reports indicate that crabgrass will grow over a wide range of soil pH values, but no research data are available evaluating the soil pH requirement of crabgrass grown as forage (3,6,16). The objective of this study was to determine the effect of varying initial soil pH levels on germination, shoot yield, and root yield of an improved crabgrass cultivar.…”

Warm-Season Grass Production Responses to Site and Defoliation Frequency

“…Yield of Red River crabgrass was substantially lower in 2002‐2003 (4000 to 6000 lb/acre) than 2001 (11,000 lb/acre) due to poor reseeding. Soil pH and MgCO 2 may have affected germination because plots were amended with dolomitic lime (4). Similar responses have been observed in West Virginia (David Belesky, personal communication , 2003).…”

Evidence That Soil Aluminum Enforces Site Fidelity of Southern New England Forest Trees

“…Sulfate (SO 4 22 ) was selected as an accompanying anion for delivery of Ca 2+ or Mg 2+ to avoid altering availability of pH-sensitive, nontarget chemical soil factors. Application of calcium sulfate fertilizer either does not affect soil pH (Pierce et al 1999) or has a slight acidifying effect (Bakker et al 1999). In our study there was an initial acidification which disappeared prior to planting the seedlings (Figure 1).…”