How soil carbon fractions relate to soil properties and crop yields in dryland cropping systems?

Abstract

Soil labile C fractions have been proposed as promising soil health indicators, but they have not been related to extensive soil properties and crop yields. We evaluated the relationships among soil organic carbon (SOC), labile C fractions, 62 soil physical, chemical, biological, and biochemical properties, and mean crop yields in two long-term (14-and 36-yr-old) sites (Froid and Sidney, eastern Montana) under dryland farming. Soil C fractions were SOC, soil inorganic carbon (SIC), waterextractable carbon (WEC), KMnO 4 -extractable carbon (POXC), potential carbon mineralization (PCM), and microbially active carbon (MAC). Treatments were conventional till and no-till spring wheat (Triticum aestivum L.)/barley (Hordeum vulgaris L.), pea (Pisum sativum L.), and fallow rotations without N fertilization in Froid and with and without N fertilization in Sidney. Carbon fractions were greater in notill continuous cropping than till crop-fallow, with no effect of N fertilization at both sites. The principal component analysis showed that PCM was strongly associated with most soil physical, chemical, biological, and biochemical properties, followed by SOC, POXC, WEC, MAC, and SIC at both sites. More C fractions were related to soil properties in longer than shorter duration of the experiment. All C fractions, except SIC, were also related to mean crop yields across years. Although SOC was related to soil properties and crop yields, PCM may be used as a promising soil health indicator because of its greater sensitivity to management practices and better relationship to soil properties and crop yields than other labile C fractions.

Arbuscular Mycorrhizal Fungi and Rhizobium Improve Nutrient Uptake and Microbial Diversity Relative to Dryland Site-Specific Soil Conditions

“…This study was conducted in contrasting dryland field sites, in Froid (48 C15 ′ 18.972 ′′ N, 104 S1). The soil is characterized as Dooley sandy loam in Froid dryland field site (DFS) 1, while DFS 2 in Sidney is Williams loam soil, as previously described by Sainju et al 2022 [29]. DFS 1 had strongly acidic soil (pH = 4.7) and low soil organic matter, while DFS2 had a slightly neutral pH (pH = 6.33) and moderate soil organic matter.…”

Relating soil physical properties to other soil properties and crop yields

“…Soil sampling to a depth of 15 cm and analysis of physical, chemical, biological, and biochemical properties were described in detail by Sainju et al 29 . The references for methods of analysis of soil properties and abbreviations of parameters are shown in Table 2 .…”

Enzyme activities as soil health indicators in relation to soil characteristics and crop production

“…In mid-July to early August, crops were harvested with a combine from a swath of 11.0 by 1.5 m and grain yield was determined after oven drying subsamples at 65 ˚C for 7 d. After grain harvest, crop residues were returned to the soil. Sainju et al (2022) described the details about soil sampling and analysis of physical, chemical, biological, and biochemical properties. The potential activity of BG was determined by using a colorimeter as p-nitrophenol released by BG when the soil was incubated with a buffered p-nitrophenyl-β-D-glucoside solution and toluene at 37 ˚C for 1 h (Tabatabai, 1994).…”