Effects of past and current crop management on soil microbial biomass and activity

Abstract

As soil biota is influenced by a number of factors, including land use and management techniques, changing management practices could have significant effects on the soil microbial properties and processes. An experiment was conducted to investigate differences in soil microbiological properties caused by long-and short-term management practices. Intact monolith lysimeters (0.2 m 2 surface area) were taken from two sites of the same soil type that had been under long-term organic or conventional crop management and were then subjected to the same 2½-year crop rotation (winter barley (Hordeum vulgare L.), maize (Zea mais L.), lupin (Lupinus angustifolius L.) rape (Brassica napus L. ssp. oleifera)) and two fertiliser regimes (following common organic and conventional practices). Soil samples were taken after crop harvest and analysed for microbial biomass C and N, microbial activity (fluorescein diacetate hydrolysis, arginine deaminase activity, dehydrogenase activity) and total C and N. The incorporation of the green manure stimulated growth and activity of the microbial communities in soils of both management histories. Soil microbial properties did not show any differences between organically and conventionally fertilised soils, indicating that crop rotation and plant type had a larger influence on the microbial biomass and enzyme activities than fertilisation. Initial differences in microbial biomass declined, while the effects of farm management history were still evident in enzyme activities and total C and N. Links between enzyme activities and microbial biomass C varied depending on treatment indicating differences in microbial community composition.

Changes in soil quality associated with tillage system applied

“…Similar results in the CO 2 evolution rate as a consequence of microbial respiration influenced by tillage system were discussed earlier by Gajda (2008), Marinari et al (2006) and Sánchez-Monedero et al (2008). It is commonly known that soil respiration is related to carbon availability in biomass and usually the greater amount of CO 2 -C is generated at the upper layer of NT soil than plowed soil because of greater population and activity of soil microorganisms (Gajda 2010;Gajda and Przew³oka, 2012;Stark et al, 2007). In our studies, the intensity of mineralization of total soil carbon (C tot ) (ratio of CO 2 -C respired and C tot ) varied with the tillage system and soil depth.…”

Effect of sorghum seedlings, and previous crop, on soil fluorescent Pseudomonas spp.

“…It is not known whether this apparent decline is due to fluctuations and variability in the percentage of Phl isolates throughout the assays, or if in further cycles, their numbers would continue to be low. Physical properties of the soil (Duffy and Défago 1999) or cropping history (Stark et al 2007) may effect populations of Phl producers.…”

A DGGE analysis shows that crop rotation systems influence the bacterial and fungal communities in soils

“…In order to elucidate the factors that may have caused this difference, we conducted a Monte Carlo test, which is one of the permutation tests suitable for investigating the statistical significance of differences within canonical correspondence analyses. Rotation times and crop types were previously shown to have some impact on microbial communities (Johnson et al 2003;Stark et al 2007), and soil chemical properties are known to affect soil biology (Sarathchandra et al 2001;Rousk et al 2010). Therefore, we analyzed the following environmental factors: (1) rotation times, (2) crop type, and (3) soil chemical properties.…”

“…Some studies have indicated that longer rotation systems that include forage or legume crops conserve soil organic matter, maintain a greater biological nutrient pool, put more nutrients into the soil, and reduce the incidence of plant pathogens, when compared with intensive rotations (Cook 2007;Janvier et al 2007;Smith and Collins 2007). Other studies have also reported that crop rotation and plant type had larger influences on the microbial biomass, enzyme activities, and microbial communities than fertilizers and soil types (Johnson et al 2003;Stark et al 2007). Additionally, several studies have identified significant differences among the microbial communities arising from different long-term cropping and management regimes, while many studies have focused on the effects of different plant species on rhizosphere microbial communities (Marschner et al 2004;Crecchio et al 2007;Larkin 2008).…”