Response of water extractable organic matter and its fluorescence fractions to organic farming and tree species in poplar and robinia-based alley cropping agroforestry systems

Abstract

Organic farming and agroforestry both have the potential to develop sustainable and environmental-friendly agroecosystems and to sequester more soil organic C (SOC). In a long-term field trial, we evaluated the effect of 21-year organic farming and 4-year agroforestry (Robinia and Poplar-based alley cropping system) on water extractable organic matter (WEOM). The technique combining excitation emission matrix (EEM) spectra with parallel factor analysis (PARAFAC) was used to reveal the components of WEOM. In addition, WEOM was characterized by UV absorbance and fluorescence spectra. Organic farming generally increased SOC and total N contents but decreased the WEOM content as well as the WEOM components indicated by the maximum fluorescence intensity (F max). Specific UV absorbance (SUVA) and humification index (HIX) of WEOM in organic farming implied WEOM in the organic farming had more components with aromatic structure but less humified. Higher fluorescence (FI) and freshness indices (BIX) of WEOM in organic farming system indicated that a higher percentage of WEOM was microbial-derived in the organic than in the integrated farming system. Robinia showed positive effect on SOC and total N contents in comparison with poplar and had stronger effects on the WEOM components, although the WEOM content did not differ between the two tree species. The significant farming × trees interactions on SOC and water extractable organic carbon (WEOC) indicated that the robinia effects were more pronounced in the organic farming system. Thus, the change of SOC was the result of interactive effect of farming and hedgerow trees in an agroforestry system. The low-input organic farming and robinia tended to result in change of quality of WEOM and led to enrichment of substances of high stability in WEOM. From above, the combination of organic farming and robinia trees is an important means for developing sustainable agricultural systems and soil carbon sequestration.

Bulk optical characterization of dissolved organic matter from semiarid wheat-based cropping systems

“…2); lower than the estimated average for arable soils (i.e. 1.50-1.90) (Hassouna et al, 2012;Sun et al, 2017). Terrestrial, plant-derived material dominated DOM fluorescence (Cory and McKnight, 2005); our sampling scheme was perhaps not deep enough to catch microbial, autochthonous signatures of DOM occurring in subsoil layers (Hassouna et al, 2012).…”

Impact of Management Practices on Water Extractable Organic Carbon and Nitrogen from 12-Year Poultry Litter Amended Soils

“…A high BIX (>1) is attributed to a predominantly autochthonous origin of WEOM and to the presence of OM freshly released into water, whereas a low BIX indicates lower autochthonous WEOM production. In addition, decomposition of the autoch- [31] and in organic farming and agroforestry soils (around 0.76) [18]. This observation suggested that the WEOM pool in these soil samples were contributed mainly from decomposed plant residues and little WEOM was derived from the fresh active crop root and indigenous microbial exudates.…”

“…The lower PLF values suggested the interference of PLF on HIX was minimal. BIX is referred as an indicator of the presence of autochthonous biological activity [23] [34], BIX has also been called a "freshness indicator" [18]. A high BIX (>1) is attributed to a predominantly autochthonous origin of WEOM and to the presence of OM freshly released into water, whereas a low BIX indicates lower autochthonous WEOM production.…”

“…Soil organic matter (SOM) plays an important role in soil quality and nutrient cycling [15]. Soil WEOM is an active, mobile and complex fraction of SOM and is sensitive to land use and management practices [16] [17] [18]. In addition, soil WEOM can contribute significant amounts of dissolved organic C and N to surface waters [19] [20].…”

Alley Cropping Meningkatkan Resiliensi Produksi Pertanian Pada Lahan Kering (A Review)

“…Robinia menunjukkan efek positif pada kandungan carbon dalam tanah dan nitrogen total dibanding poplar, dan memiliki efek lebih kuat pada komponen kandungan bahan organik, walaupun tidak berbeda antara dua jenis pohon. Dari sini diketahui pula, penyebaran bakteri organik dan mikroorganisme bermanfaat bagi pengembangan sistem pertanian dan penyerapan karbon tanah (Sun et al, 2017). Neupane and Thapa (2001) Tanaman hedgerow yang digunakanGliricidia sepium, Paspalum conjugatum, dan Penisetum purpureum.…”