Residual effects of combinations of limestone, zinc and manganese applications on soil and plant nutrients under mild and wet climatic conditions.

摘要

A field trial from 1979 through 1993 with three limestone and five zinc (Zn) and manganese (Mn) treatments applied at various intervals on several different crops was used to assess residual treatment effects on crop yields and nutrient contents, and Mehlich-3 soil element extractions. Limestone (0, 9 and 19 Mg ha-1) was applied in 1979, 1981 and 1986. Micronutrients (Zn at 2.3 kg ha-1 (Zn), Mn at 2.3 kg ha-1 (Mn1) and 4.5 kg ha-1 (Mn2), and Zn+Mn1) were applied to the foliage of cauliflower in 1979, 1980, 1982, 1984 and 1985, and incorporated into the soil in 1988, 1989 and 1990 prior to growing oats. From 1991 through 1993, the test crop was orchard grass (Dactylis glomerata L.). The historic limestone treatments that were completed in 1986 continued to affect grass growth with up to 7% increase with high limestone rate in cut #2 in 1993. The historic micronutrient treatments (completed in 1988) also affected grass yield to mid-1993, but the nature of the effects was variable (increases, decreases and no effects depending on limestone treatments and micronutrient rate combinations). Concentrations of Ca extracted from the soil in 1993 increased to 60-cm depth with limestone applications. Soil extractable Zn and Mn decreased in response to increased historic limestone applications. The historic Zn and Mn applications increased extractions of corresponding nutrients in surface 15 cm of soil sampled in fall 1993. Limestone applications decreased total C and N in the soils, which has implications on N management and C sequestration. Limestone decreased the apparent availability of several non-treatment nutrients (K, Mg, Na, S and Fe), which could reduce the intended benefit of applying limestone.