[Effects of Different Cropping Systems on Soil Quality in Paddy Fields of Southern Henan]

To investigate the effects of different rice-based cropping systems on soil quality in paddy fields of southern Henan， a long-term （6-year） experiment with five distinct cropping systems was conducted： fallow-rice rotation （F）， wheat-rice-rapeseed-rice rotation （WR）， green manure-rice-wheat-rice-rapeseed-rice rotation （GWR）， green manure-rice-wheat-rice rotation （GW）， and wheat-rice-green manure-rice-green manure-rice rotation （WGG）. Soil quality was comprehensively evaluated through physicochemical properties， aggregate characteristics， and enzyme activities to identify key indicators. The results showed that compared with that under the intensive planting system （WR treatment）， the GWR， GW， and WGG treatments （incorporating green manure into the planting system） significantly reduced soil bulk density （BD） by 12.80%-23.68% and increased soil organic carbon （SOC） content by 43.87%-90.88% and total nitrogen （TN） content by 18.52%-77.78%， while the seasonal fallow planting system （F treatment） also significantly increased SOC content by 83.33% and TN content by 34.57%. The GWR， GW， WGG， and F treatments significantly reduced the average mass fraction of aggregates with a particle size of <0.25 mm by 21.87%-53.24% compared to that under the WR treatment， while it significantly increased the average mass fraction of aggregates with a particle size of >5 mm and 0.25-2 mm， thereby improving the average weight diameter （MWD） of aggregates. Moreover， the GW， WGG， and F treatments also significantly increased the SOC and TN contents of various particle sizes compared to those under the WR treatment. Correlation analysis also showed that the SOC and TN contents of all particle sizes （except TN in 2-5 mm） were significantly positively correlated with MWD （P<0.05）. The C-acquiring enzymes activity （C-acq） and N-acquiring enzymes activity （N-acq） of the GWR， GW， and WGG treatments were significantly higher than those of the F treatment， ranging from 44.02% to 66.66% and 54.16% to 88.72%， respectively. Compared with that of the WR treatment， the C-acq of the F treatment was significantly increased by 44.20%， but there was no significant difference between N-acq and the WR treatment. The soil quality index （SQI） of the GWR， GW， WGG， and F treatments significantly increased by 53.09%-109.20% compared to that of the WR treatment， with WGG showing the greatest improvement. Correlation analysis showed that SQI correlated positively with MWD， SOC， TN， and C-acquiring enzymes （P<0.01） and negatively with BD （P<0.05）. Random forest analysis identified MWD， TN， SOC， and C-acquiring enzymes as primary determinants of SQI （P<0.05）. In summary， these findings demonstrate that long-term green manure incorporation enhances soil physicochemical properties， aggregate stability， and enzymatic activity， thereby improving paddy soil quality and supporting regional agricultural sustainability.