The Screening Of Soil Amendments And Their Improvements On Sports Turf

Sports turf, which is different from the landscape turf, should receivevery heavy traffic from sports activities and maintenance mechinary. Thedaily heavy traffic on the sport turf resulted in soil compaction and lessoxygen limiting the turfgrass root growth and respiration and finally led toturf degradation. To reduce the soil compaction, sand in medium andcoarse particle sizes are recommended to used as the rootzone materials forsports turf fields. However, sand-based rootzone has very low capacity inwater and nutrient retentions. The frequent irrigation and fertilizeringprograms are need to maintain the turfgrass vigor. Mixed with soilamendments into the sand-based rootzone is a major way to improve thewater and nutrition retention in sports turf. In this paper, the physical andchemical properties of the different soil amendments and theirimprovements by various ratios mixed with sand were evaluated, Theimpacts of candidate soil amendments added into sand rootzones onturfgrass establishment, nutrient leaching and drought resistence were alsostudied. The results were:(1) The physical and chemical properties of8different soil amendments were evaluated. Two samples of coral sands and a sample ofvermiculite did not show significant difference in hydraulic conductivity,porosity, bulk density, water retention, when compared with the sandcontrol, indicating that these materials have no significant improvement forthe sand-based rootzone and is not suitable for candidate amendments forsports turf rootzones. Peat moss showed the significant higher waterretention and lower bulk density than the sand control, but the significantlower hydraulic conductivity and porosity of peat moss indicated itsdrewback for rootzone improvement. Profile porous ceramics and Axisdiatomaceous earth showed the significant better properties in hydraulicconductivity, porosity, bulk density and water retention, indicating they aregood candidate amendments for the rootzone improvement. Rice-huskbiochar and Clite perlite showed the same properties in hydraulicconductivity and porosity as Profile and Axis and the better properties inbulk density and water retention than Profile and Axis, indicating theirapplication prospect as rootzone amedments in sports turf.(2) The serious ratios of5candidate amendments including rice-huskbiochar, Clite, Profile, Axis and peat moss mixed with sand were evaluatedfor the improvement of the rootzone properties. The results showed thatrice-husk biochar, Clite, Profile and Axis significantly increased therootzone hydraulic conductivity, total and capillary porosity, waterretention, K+and NO3-retention. These increases were positively relatedto the ratios of amendments added. As the ratios of rice-husk biochar andClite beyoung the15%, the rootzone capillary porocity exceed the highestvalue of USGA recommendation (25%). As the ratios of Axis beyoung the15%, the rootzone total porocity exceed the highest value of USGA recommendation (50%). As the ratios of Profile beyoung the20%, therootzone non-capillary porocity exceed the highest value of USGArecommendation (30%). Peat moss reduced rootzone hydraulicconductivityand non-capillary porosity. As the ratios of peat moss beyoungthe10%, the rootzone non-capillary porocity decreased below the lowestvalue of USGA recommendation (15%). The results indicates that thehighest ratios of amendments added into sand were: rice-husk biochar≤15%; Clite≤15%; Axis≤15%; Profile≤20%; peat moss≤10%.(3) Effects of5candidate amendments on creeping bentgrass(Agrostis stolonifera L.) establishment was evaluated. The results showedthat all amendments added into the sand rootzone improved the retentionof moisture and K+, NO3-, but the peat moss treatment significantlydecreased the saturated hydraulic conductivity. All soil amendmentsimproved the seed germination and seedling growth of creeping bentgrasswith the performance in leaf emergence, tillers per plant, growth rate,biomass and turf coverage. The order of improvement was: Profile> peatmoss> Axis> rice-husk biochar> Clite. The order of root effect wasdifferent from that of the shoot and Profile showed the best in root biomass,followed by Clite, peat moss and rice-husk biochar, but Clite was the bestin root length, followed by Profile, Axis, rice-husk biochar and peat moss.(4) Effects of4candidate amendments on drought resistance ofhybrid bermuda grass(Gynodon dactylon×C. transvaalensis) wereevalutaed. The results showed that all candidate amendments added intorootzone inproved the drought resistance of bermudagrass, when comparedwith the sand control. Clite performed the best in drought resistanceimprovement, followed by Axis, Profile and rice-husk biochar, indicated by leaf electrolyte leakage, chlorophyll content, relative water content androot biomass. The improvements of drought resistance of Axis and Profilewere positively related to the ratios added into the rootzone. However, thebest improvements of Clite and rice-husk biochar occurred in10%treatments. The treatments of15%showed the lower drought resistancethan10%, but still higher than5%treatments.(5) Effects of5candidate amendments on the leaching of nitrogenand potassium from the mature turf were evaluated. The results showedthat all amendments (10%) added into the sand rootzone significantlydecreased the leaching of nitrogen and potassium, when compared with thesand control. The total N leaching in the control reached as high as38.4%,but all5amendments treatments decreased the leaching below25.1%.NO3was the main leaching form in turfgrass rootzone and NH4+wasminor in the leaching solutions. The order of N leaching improvement was:Clite> peat moss> rice-husk biochar> Profile>Axis. The K+leaching inthe control reached as high as44.8%, but all5amendments treatmentsdecreased the K+leaching below29.2%. The order of K+leachingimprovement was: peat moss> Clite> rice-husk biochar> Profile>Axis.Five amendments significantly increased the N and K retention in therootzone, which improved the growth of creeping bentgrass with thehigher growth rate, turf quality, leaf chlorophyll content, biomass and turfdensity than the control after leaching. The order of creeping bentgrassimprovement was: peat moss> Profile> rice-husk biochar> Axis> Clite.(6) Compared with Axis diatomaceous earth and Profile porousceramics, Clite perlite has the better improvements in water retention,drought resistance, and nutrients leaching. Rice-husk biochar also has the better improvements in water retention and nutrients leaching. The resultsshowed that Clite and rice-husk biochar were good candidate soilamendments for rootzone improvement in sports turf.