No-tillage agriculture can sustain productivity and protect the environment. A comprehensive understanding of soil arbuscular mycorrhizal (AM) fungal diversity and soil carbon distribution within aggregate fractions is essential to the evaluation of no-tillage agriculture. The long-term field experiment included two tillage treatments (1) no tillage with straw returned to the soil (NTS), and (2) conventional mouldboard-plowing tillage without straw (CT), and was conducted on the Loess Plateau, north-western China, from October 2009. The soil samples were collected from the surface layer (0–20 cm depth) at the maturation stage of the summer maize (Zea mays L.) for analyzing aggregates separated by the dry-sieving method. The organic carbon content in the bulk soil and different particle size aggregates were measured using the dichromate oxidization method. The species compositions of soil AM fungi were compared by applying high-throughput sequencing of 18S rRNA. The results showed that the NTS had 9.1–12.2% higher percentage of soil macro-aggregates, resulting in 9.8% increase in mean weight diameter and 10.0% increase in bulk soil organic carbon content as compared with CT treatment. In addition, the NTS treatment had significantly higher percentages of Septoglomus and Glomus than the CT treatment. We also found some significant differences in the fungal communities of the soils of the two treatments. There was a strong positive relationship between bulk soil organic carbon and the percentages of Septoglomus and Glomus. Our results suggested that the NTS treatment had a protective effect on AM fungal community structures, which might play a key role in the development of agricultural sustainability in the Loess Plateau of China.

Tillage disturbance can affect carbon dynamics in soil and plant production through several mechanisms. There are few integrated studies that have dealt with the effect of tillage management on soil CO2 emission and yield of wheat grain (Triticum aestivum L.) in the Loess Plateau in China. A 3-year (2010–12 and 2013–14) field experiment with two types of tillage was established to investigate CO2 emission, its related soil properties, crop yields and yield-scaled CO2 emissions (CO2 emissions per unit crop production) under rain-fed field conditions. Some land was planted with winter wheat without using tillage (‘no tillage’; NT), whereas some used mouldboard plough tillage (‘conventional tillage’; CT). The results indicate that CO2 was significantly and positively related to total nitrogen (P < 0.01), soil organic matter (P < 0.01), soil enzymes (P < 0.01; urease, invertase, and catalase), soil temperature (P < 0.01) and total pore space (P < 0.05). Multiple linear regression analysis in the NT plot included soil temperature and air filled pore space, explaining 85% (P < 0.05) of the CO2 variability, whereas in the CT plot the multiple linear regression model included soil temperature, urease, bulk density and pH, explaining 80% (P < 0.001) of the CO2 variability. Compared with the CT treatment, NT reduced the 3-year average yield-scaled CO2 emissions by 41% because of a 40% reduction in total CO2 emissions with no reduction in wheat yield. Thus, the results indicate that NT could be used to reduce the contribution of agriculture to CO2 emissions while simultaneously maintaining wheat crop production in this area.

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The idea of mitigating anthropogenic CO2 emissions by increasing soil organic carbon (SOC) is notable. However, the estimation of the net ecosystem carbon balance after conversion from conventional tillage to conservational tillage has been poorly quantified for the Loess Plateau in China. A 2-year field experiment was conducted to estimate the agroecosystem carbon balance of a winter wheat–summer maize rotation system using a full carbon cycle analysis. The results showed that a positive net ecosystem carbon balance value in the cases of rotary tillage with straw incorporation, chisel plow tillage with straw incorporation, and no tillage with straw mulching treatments. Note that a negative value was detected for the conventional moldboard plowing tillage without crop straw treatment. The conversion from conventional tillage to conservational tillage substantially enhanced the carbon sink potential from 0.84 t C ha−1 yr−1 to 2.69 t C ha−1 yr−1 in both years. Our findings suggest that the expansion of conservational tillage could enhance the potential carbon sink of the rain-fed land in China.

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