Tea Bag Index to Assess Carbon Decomposition Rate in Cranberry Agroecosystems

Abstract

In cranberry production systems, stands are covered by 1–5 cm of sand every 2–5 years to stimulate plant growth, resulting in alternate layers of sand and litter in soil upper layers. However, almost intact twigs and leaves remain in subsurface layers, indicating a slow decomposition rate. The Tea Bag Index (TBI) provides an internationally standardized methodology to compare litter decomposition rates (k) and stabilization (S) among terrestrial ecosystems. However, TBI parameters may be altered by time-dependent changes in the contact between litter and their immediate environment. The aims of this study were to determine the TBI of cranberry agroecosystems and compare it to the TBI of other terrestrial ecosystems. Litters were standardized green tea, standardized rooibos tea, and cranberry residues collected on the plantation floor. Litter decomposition was monitored during two consecutive years. Added N did not affect TBI parameters (k and S) due to possible N leaching and strong acidic soil condition. Decomposition rates (k) averaged (mean ± SD) 9.7 × 10−3 day−1 ± 1.6 × 10−3 for green tea, 3.3 × 10−3 day−1 ± 0.8 × 10−5 for rooibos tea, and 0.4 × 10−3 day−1 ± 0.86 × 10−3 for cranberry residues due to large differences in biochemical composition and tissue structure. The TBI decomposition rate (k) was 0.006 day−1 ± 0.002 in the low range among terrestrial ecosystems, and the stabilization factor (S) was 0.28 ± 0.08, indicating high potential for carbon accumulation in cranberry agroecosystems. Decomposition rates of tea litters were reduced by fractal coefficients of 0.6 for green tea and 0.4 for rooibos tea, indicating protection mechanisms building up with time in the tea bags. While the computation of the TBI stabilization factor may be biased because the green tea was not fully decomposed, fractal kinetics could be used as additional index to compare agroecosystems.

CO2 Emissions in Layered Cranberry Soils under Simulated Warming

“…Soil Taxonomy, and Orthic Podzols in the World Reference Base for Soil Resources. The soil contained 937 g sand kg −1 , 37 g silt kg −1 , and 26 g clay kg −1 at site #45, and 915 g sand kg −1 , 49 g silt kg −1 , and 36 g clay kg −1 at site #9 [4].…”

“…As a result, soil respiration is greater near soil surface (0-5 and 5-10 cm layers) compared to lower layers [46]. The cranberry litter deposited on the floor of cranberry beds contains approximately 80% of lignocellulose while 89% of the particles are larger than 2 mm in size and the C:N ratio is 55 in average [4]. Lignocellulose is a compact material made of strongly bound cellulose, lignin, and hemicellulose in structural networks in stems and roots [47].…”

“…While soil C sink capacity of managed ecosystems is the estimated historic cumulative C loss of 55-78 Gt, the attainable capacity is only 50-66% of that potential [3]. Cranberry agroecosystems are exceptions to this general perspective [4]. The fate of organic matter in soils depends primarily on its intrinsic decomposability and on protection mechanisms such as soil aggregation [5] in silty or clayey agricultural soils [6].…”

“…The overgrowth of uprights is buried every 2-5 years by spreading two to five cm of sand onto frozen soil to promote new growth [9]. This results in alternate layers of sand and organic matter in the root zone [10] and high potential for C storage due to physical protection through anthropic surface sanding [4].…”

Protocol of conjugate evaluation of the biological activity of soils in terms of cellulolytic activity and biological consumption of oxygen

“…Soil organic matter decomposition is a fundamental ecosystem process that allows for the cycling of nutrients. The rate of organic matter decomposition is measured using various test objects, such as filter paper [1] , [2] , [3] , [4] , linen [ 5 , 6 ] or cotton [7] , [8] , [9] fabric, tea bags [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , components of woody or herbaceous plants (needles, leaves and branches) [ 11 , [17] , [18] , [19] ]. Recently, the tea bags have become the most widely used among them with the subsequent calculation of a Tea Bag Index (TBI) [ 10 , [20] , [21] , [22] ] proposed by [23] .…”