274 (Table 2). Soil NH4 Scharenbroch et al.: Biochemical Properties and Dentrification in A and Bt Soils pared to water in the A horizon soil (Table 2). No differences were observed for these N pools between the ACTd + was greater with ACTc and water, in either soil type. In a typical soil (1.0 Mg m-3 25 cm), 50 mg kg-1 N would equate to 127 kg N ha-1 able N pools of NH4 , NO3 + ACTc and fertilizer com- treatments , and would and top fall within the current ANSI standard fertilization application rate of 98 to 195 kg N ha-1 study indicate that none of the A horizon soils would be defi- cient in N (68.3, 80.5, 82.7, and 114.9 mg kg-1 , and fertilizer, respectively). Nitrogen deficiencies may ex- ist with the Bt soils for the water (18.4 mg kg-1 (21.3 mg kg-1 ACTc and fertilizer both increased soil NH4 (60.7 mg kg-1). The findings of this study demonstrate that fertil- izer is best at increasing NO3 and DON levels in the soil, but kg-1), and ACTc ), but not for the fertilizer treatment - for water, ACTd ), ACTd + in A horizon soils. Soil Microbial Biomass, Respiration, N Mineral- ization, and Denitrification In the A horizon soils, MBN was 67, 44, and 39% greater with fertilizer compared to water, ACTd , and ACTc , (19.4 mg (ANSI 2004). Combining the plant avail- -, DON, and MBN, the results of this ble 2). Microbial biomass N in the Bt horizon with fertilizer was 216%, 216%, and 182% greater compared to water, ACTd , and creased with either ACT treatment compared to water (Table 2). The researchers conclude that a one-time fertilizer application increased the existing soil microbial biomass N pool in excess of the microbial biomass N added in a one-time ACT treatment. The Solvita test CO2 ACTc, respectively (Table 2). Microbial biomass N was not in- ceeded water at all times and both soil types (sans hour 196 for the Bt horizon) (Figure 1). CO2 efflux was greater with fertilizer compared to ACTc at hours 12 and 196 for the A ho- efflux with ACTc rizon soil, and at hours 12, 24, 48, and 96 for the Bt horizon soils (Figure 1). With the A horizon soils, CO2 , respectively (Ta- compared to water, temporarily increases microbial respira- tion. Larkin (2008) showed significantly greater microbial substrate utilization in Biolog plates with ACT compared to for the Bt horizon soils (Figure 1). The data show that ACTc was greater than water at hours 12 and 24 (Figure 1). At hours 12, 24, 48, and 96 ACT CO2 efflux exceeded water , and fertilizer were greater than water for the A horizon soils (Table 2). No differences were observed for RES among the treatments for the Bt horizon soils. Fertilizer CO2 respiration (RES) values for ACTc efflux ex- ter under saturated conditions over a 192-hour laboratory assay. Each point is a mean of six replicates, with error bars showing standard error of the mean. P-values are given for each ANOVA at each collection time. Unique letters identify differences with Tukey’s HSD test. Means, standard errors, and Tukey’s HSD differences are also listed for samples averaged over the entire 192-hour assay. Figure 1. CO2 and N2 O efflux from A and Bt horizon soils treated with concentrated aerobic compost tea (ACTc ©2011 International Society of Arboriculture ), fertilizer, or deionized wa-
November 2011
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
