Improvement of soil structure through organic crop management, conservation tillage and grass-clover ley

Abstract

Conventional tillage is a widespread soil management practice that controls weeds and promotes nutrient mineralization at the expense of a degraded soil structure and soil carbon (C) loss. Although C dynamics and soil structure are widely recognized as pivotal to essential environmental and crop-related agroecosystem processes such as belowground C storage and crop root establishment, there is still a need to evaluate cropping practices most favorable for soil structure. For example, the effects on soil structure by continuous intensive tillage after a ley period remains unclear. To address these issues, we measured mean weight diameter, total C and total nitrogen (N) in whole soil and water-stable aggregate fractions after a 4-year arable crop rotation on a Cambisol where organic and conventional management was combined with intensive tillage and different types of conservation tillage. Measurements were repeated following a 2-year grass-clover ley period. Results showed that 4 years of organic management (including the application of cattle manure slurry) combined with reduced tillage significantly improved soil structure through increasing the proportion of large macroaggregates and hence the aggregate mean weight diameter (MWD) in the 0-6 cm soil layer. Although an increase in MWD after ley was observed in organic intensive tillage and a marginal increase in conventional intensive tillage, a significant increase in total C was observed only for the organic cropping systems, which also showed a high C stratification between 0-6 cm and 6-20 cm depth. Thus, a ley period enhances soil structure after continuous cropping under intensive tillage and when organic management is combined with reduced tillage. In conclusion, soil structure is best maintained when combining organic management with reduced tillage due to additive effects.

Conservation tillage and organic farming reduce soil erosion

“…Moreover, SOM increased considerably in FAST from 2014 to 2017 and was the highest in O-RT in both years. This finding could be explained by the 2year grass-clover ley that was grown between winter wheat and maize within the FAST rotation and is known to increase SOM in agricultural soils (Loaiza Puerta et al 2018). The increased SOM content in the topsoil layer in O-RT might be attributed to the combined effect of organic fertilization and reduced tillage intensity.…”

“…Loaiza Puerta et al (2018) reported that organic management together with reduced tillage significantly improved the soil structure in the FAST experiment. Conservation tillage can promote aggregation of microaggregates into macroaggregates compared to intensive tillage (Six et al 2000b), and macroaggregate turnover is lower under reduced tillage (Six et al 2000a).…”

Changes in soil macropores: Superposition of the roles of organic nutrient amendments and the greenhouse pattern in vegetable plantations

“…Under mineral fertilization conditions, greenhouse systems are recognized as an intensive agricultural practice that leads to land degradation (Yang, Hao, Li, & Li, ), while the organic greenhouse system had a significant positive effect on soil pores, leading to improved crop yield and soil quality (Schrama et al., ). We believe that the principal factor explaining this pattern is organic fertilization, which is regarded as a traditional method for improving soil porosity and enhancing water–air transmission (Conacher & Conacher, ; Loaiza Puerta et al., ). A 37‐year field experiment on the effects of soil properties in Switzerland also showed that organic management supplied a 25 to 80% greater C input to the soil than did mineral fertilization and resulted in better physical properties (Maltas et al., ).…”

“…Similar results were obtained by Papadopoulos, Bird, Whitmore, and Mooney () with X‐ray computed tomography (CT) scanning in the UK. In addition, several researchers have examined the effect of organic fertilization on soil pores under other beneficial modes of tillage (Cogger, Bary, Myhre, Fortuna, & Collins, ; Loaiza Puerta, Pujol Pereira, Wittwer, van der Heijden, & Six, ). For example, Loaiza Puerta et al.…”

“…For example, Loaiza Puerta et al. () found that no tillage, reduced tillage and temporary leys could minimize the negative effect of intensive tillage on soil structure, among which the most obvious improvement in soil structure was observed under reduced tillage combined with organic crop management.…”