Intercropping affects the rate of decomposition of soil organic matter and root litter

Abstract

Aims Intercropping increases aboveground and belowground crop productivity, suggesting potential for carbon sequestration. Here we determined whether intercropping affects decomposition of soil organic matter (SOM) and root litter. Methods We measured in the laboratory and the field the breakdown of SOM, root litter of maize, wheat, or faba bean, litter mixtures, and a standard substrate (compost) in soils from a long term intercropping experiment. Results Soil organic matter from intercrop plots decomposed faster than SOM from monocrop plots, but compost decomposed at similar rates in different soils. Faster SOM decomposition was associated with lower soil C:N ratio. Root litter mixtures of maize and wheat decomposed as expected from single litters, but litter mixture of maize and faba bean decomposed faster than expected, both in the laboratory and in the field. Root litter decomposed slowly in maize/wheat intercrop soil compared to the two monocropped soils in the laboratory, but the effect was absent in the field. Conclusions Intercropping increases SOM decomposition, presumably through reduced SOM recalcitrance resulting from lower C:N ratio, higher litter input and better N retention. Depending on the crop combination, also non-additive effects of root litter mixing can enhance organic matter decomposition in intercropping soils.

Soil microbiological properties and available nitrogen for corn in monoculture and intercropped with forage

“…Moreover, under NT systems, corn roots, which are more concentrated in surface soil layers (Silva et al, 2000), together with the deposition of plant residues, may have also contributed to increases in TOC and TN. It should be noted, that although the enhanced levels of TN may also be attributed to N fertilization in corn, the simultaneous increase in TOC suggests the possibility of synergy between C and N, whereby C sequestration enhances N sequestration, and vice versa (Cong et al, 2015). Diógenes et al (2013) found higher TOC values for corn intercropped with U. ruziziensis, when compared to this forage in monoculture.…”

“…However, differences in plant residue quality and chemical composition may affect SMB growth (Ferreira et al, 2011;Cong et al, 2015), which, in turn, may be positively related to N (NO 3 -and NH 4 + ) mineralization potential in the soil and, consequently, to its uptake by SMB (Burger & Jackson, 2003). Dourado-Neto et al (2010) highlighted that, in tropical agroecosystems, soil N pool can provide up to 79% of the total N uptake by plants, showing the importance of SOM preservation and of plant residue inputs for N availability to crops.…”

Effects of bio‐based residue amendments on greenhouse gas emission from agricultural soil are stronger than effects of soil type with different microbial community composition

“…Hence, our results question the extent of using C : N ratios alone to predict the soil response to residue input and consequences for greenhouse gas flux. While we cannot completely exclude a priming effect causing increased soil respiration following residue amendments (Fontaine et al ., ; Cong et al ., ), significant CO 2 release coupled to a relatively higher biomass loss of the same residues suggest that the newly added carbon source, rather than the existing carbon fraction in the soil was mineralized, in which case, priming effect would be minimal.…”

On yield gains and yield gaps in wheat-maize intercropping : opportunities for sustainable increases in grain production

“…Chinese researchers have actively engaged in quantitative studies on wheat-maize intercrop performance over the last two decades. Studies focused on quantification of yields (Li et al, 2001b), radiation use efficiency and water use efficiency (Fan et al, 2013), analyses of the soil carbon and nitrogen sequestration in the long term (Cong et al, 2015a;Cong et al, 2015b) and greenhouse gas emission Hu et al, 2016), and exploration of belowground root interactions in terms of nutrient mobilization and nutrient transfer between species (Zhang and Li, 2003). Often positive effects were found in those studies, such as higher land use efficiency, higher water use efficiency, greater carbon and nitrogen storage and less greenhouse gas emission per hectare in wheat-maize intercropping compared to sole wheat or sole maize.…”

“…Development of machinery for cultivating and harvesting intercrops is required to overcome this constraint. A market for such machinery may develop if the advantages of intercropping (high yield, better resource capture, building of soil organic matter, suppression of pests and diseases) are substantial and recognized (Brooker et al, 2015;Cong et al, 2015a).…”