Effect of border irrigation co-applied with super absorbent polymers on micro-environment characteristics in the rhizosphere soil and growth of Populus euramericana cv. ‘Neva’

ObjectivesTo explore effect of border irrigation co-applied with super absorbent polymers (SAP) on micro-ecological environment characteristics in the rhizosphere soil and growth of Populus euramericanacv. ‘Neva’.

MethodsA field experiment with five treatments, i.e. CK (conventional border irrigation), BI₆₀(60% conventional border irrigation quantity), BI₃₀(30% conventional border irrigation quantity), BI₆₀S (60% border irrigation quantity co-applied with SAP) and BI₃₀S (30% border irrigation quantity co-applied with SAP) was conducted to determine effects of different treatments on root exudate, physico-chemical characteristics, microbial population in the rhizosphere soil and growth of Populus euramericanacv. ‘Neva’.

ResultsCompared with the CK treatment, the total organic acids and total amino acids in the root exudates in the BI₆₀S treatment were significantly increased by 15.13% and 9.23%, respectively. The BI₆₀and BI₃₀treatments obviously increased pH values in the rhizosphere soil, while the pH values appeared a decreasing trend in the treatments of BI₆₀S and BI₃₀S, and the pH values in the BI₆₀S treatment were decreased by 0.21, 0.48, 0.66 and 0.26, respectively, compared with the treatments of CK, BI₆₀, BI₃₀and BI₃₀S. The contents of available nitrogen, available phosphate and available potassium were significantly increased by the BI₆₀S treatment, showing 16.72%, 23.98% and 20.11% increases compared with the CK treatment. The contents of moderate-labile organic carbon and low-labile organic carbon in the treatments of BI₆₀and BI₃₀were notably decreased, while the BI₆₀S and BI₃₀S treatments could apparently increase the corresponding contents. The BI₆₀S treatment also significantly increased the populations of bacteria, actinomyces and fungi, and the contents of microbial biomass carbon and microbial biomass nitrogen, with 11.93%, 62.74%, 122.28% and 16.33% increases in bacterial population compared to the treatments of CK, BI₆₀, BI₃₀and BI₃₀S, respectively. Furthermore, the average growth rates of diameter at the breast height (DBH), tree height and volume in the BI₆₀S treatment were 25.37%, 23.59% and 64.06%, respectively, which were also obviously higher than other treatments. However, in the BI₃₀S treatment, fewer effects on rhizosphere soil and growth of poplar were observed compared with the BI₆₀S treatment.

ConclusionThe measure of 60% border irrigation quantity co-applied with super absorbent polymers was more beneficial to improving ecological environment in the rhizosphere soil and promoting growth of Populus euramericanacv. ‘Neva’.