Soil Fertility,Microbial Biomass,and Microbial Functional Diversity Responses to Four Years Fertilization in an Apple Orchard in North China

Soil microbial communities play an essential role in maintaining soil fertility and are considered as ecological indicators to evaluate soil health.In the present study,we examined the influence of almost 4 years of fertilization[no fertilizer(CK),nitrogen alone(N),nitrogen,phosphorus and potassium chemical fertilizer(NPK),organicmanure(M),nitrogen plus organic manure(NM),and NPK plus organic manure(NPKM)]on soil fertility and the functional diversity of soil microbial communities in an apple orchard.Compared to CK,fertilization increased soil organic carbon,total nitrogen,and available nutrients,but reduced soil pH in N and NPK treatments.The highest microbial biomass carbon and nitrogen,most probable number of actinomycetes,bacteria,and fungi occurred in the NPKM treatment.The average well color development(AWCD)values followed the order of NPKM>M>NPK and NM>CK and N.The Shannon index in organic manure treatments were significantly higher than in control and in treatments without organic manure.The principal component analysis showed that manure treatment was significantly separated from other treatments.These results indicated that organic manure applied alone or in combination with chemical fertilizers would increase soil fertility and functional diversity of soil microbial communities.Moreover,applying balanced N,P,K fertilizer in combination with organic manure was found to be superior to the use of a single fertilizer in improving soil microbial community quality.

Changes in soil organic carbon,nitrogen and sulphur along a slope gradient in apple orchard soils of Kashmir Himalaya

Accumulation and losses of soil organic carbon(SOC),total nitrogen(TN)and sulphur(S)influence food security and global warming.Therefore,their spatial distribution and variability at regional scale,and their relation to topographical variables are of great interest.In this study,the variability of SOC,TN and S content was evaluated in apple orchard soils of Kashmir region,at three depths(D1:0-10,D2:10-20,and D3:20-30 cm)on slope gradient i.e.:flat,medium,and high.With an increase in slope,a significant decrease of SOC and TN was observed,with concentration of SOC and TN recorded highest(14.3±2.06 g kg-1&0.97±0.35 g kg-1)in flat slope orchards and lowest(9.6±2.07 g kg-1&0.84±0.41 g kg-1)in high slope orchards.On stock basis,the values recorded for flat,medium,and high slope orchards,for SOC and TN were 54.62±4.24 Mg ha-1&0.38±0.06 Mg ha-1,44.13±5.11 Mg ha-1&0.32±0.09 Mg ha-1,and 38.73±5.94 Mg ha-1&0.28±0.10,respectively.The differences for S concentration and stocks were modest,with flat(0.21±0.15 mg kg-1&0.09±0.0.003 Mg ha-1)>high(0.16±0.07 mg kg-1&0.06±0.007 Mg ha-1)>medium(0.12±0.04 mg kg-1&0.075±0.009 Mg ha-1).Across slopes,SOC,TN and S decreased with increasing soil depth,suggesting clear downward trend.Overall,SOC and TN increased with the increase of altitude,precipitation and clay content while its relationship with soil acidity and soil bulk density was negative.The findings may provide scientific basis to structure agricultural development plans or prioritize regions for soil conservation efforts.

Evaluation on Application and Spraying Effect of Air-Assisted Sprayer in Apple Orchard with Dwarfing Rootstocks

The application and spraying effect of 3 WG-1200 A air-assisted sprayer in dwarfing rootstock apple orchard were evaluated by investigating the droplet density, coverage and volume median diameter(VMD) in different canopy layers(2.0, 1.5, 1.0 m) and five directions(east, south, west, north and middle) of apple trees. The results showed that the droplet density was 166.99 per square centimeter, the coverage was 48.23%, and the VMD was 138.63 μm. The droplet density in different canopy layers of the trees had consistent trend with the coverage. The droplet density and coverage in the upper and middle canopy(2.0 m and 1.5 m) had no significant difference, but they were both higher than those in the lower canopy, while the VMD in different canopy layers showed an opposite trend. The change trends of the coverage and VMD in the five directions were consistent, and the values in the middle and east were the highest, followed by the north, south and west, respectively. The results indicated that droplet characteristics of the 3 WG-1200 A air-assisted sprayer met the basic requirements for pest and pathogen control. This study provides a theoretical basis and data support for the application and improvement of orchard application equipments in dwarfing rootstock apple orchard.

Propagation model for 2.4 GHz wireless sensor network in four-year-old young apple orchard

Wireless sensor network(WSN)nodes exchange information via wireless signals,whose power can attenuate at different levels according to the propagation environment.The branches and leaves of young apple trees are much sparser than that of adult apple trees.Propagation rules such as propagation distance and attenuation rate are the parameters necessary to know before applying a WSN to a young apple orchard.Field tests were performed,and propagation distance and packet loss rate(PLR)were computed and compared under the two cases:a young apple orchard in fruit period and an open space to find the effect of the apple trees on radio propagation.A model of antenna height and propagation distance was created to forecast the extra path loss caused by the young trees.Validation experiments were performed in a different young apple orchard,and the validation results showed that 70% of R^(2) were higher than 0.7,while the smallest being 0.65;80% RMSE were smaller than 5.The new model was also compared with some classical models such as Cost 235,FITU,ITU-R,and Weissberger model,and the new model was proved to be the best.

Effect of Conservation Tillage Practices on Soil Phosphorus Nutrition in an Apple Orchard

Soil phosphorus(P) is an essential and limiting element for plant growth, which is significantly affected by different approaches to soil management. In order to reveal the effect of different management approaches on soil P and phosphatase activity in 0–20 cm and 20–40 cm soil, this research was conducted to study variations in the characteristics of P and phosphatase activity under 3-year tillage without mulching(CK), notillage with corn straw mulching(NTSM) and no-tillage with grass(NTG) in Liaoning apple orchard. The results showed that NTSM and NTG could significantly increase soil P content(P < 0.05) as compared with CK. However, the effect was different between NTSM and NTG; with the NTSM approach, the improvement in the P content in 20–40 cm was remarkable, and in the NTG approach, the improvement in the soil surface P content was significant. At the same time, soil phosphatase activity significantly increased(P < 0.05) under NTSM and NTG. The soil surface and 20–40 cm phosphodiesterase(PD) activity was enhanced under the two management approaches, however, the effect of NTG was stronger than NTSM. In addition, NTSM was more conducive to increasing alkaline phosphomonoesterase(Al P), and NTG was more conducive to increasing acid phosphomonoesterase(Ac P). Our findings highlight the variation of dominant mechanisms involved in soil P with different mulching materials application. NTSM and NTG could have the potential to increase P content and phosphatase activity, and provide a basis for using this method to improve P phytoavailability and reduce the application of soil fertilizer.

Nitrogen distribution in apple orchard soil profile under fertilization with different water and fertilizer coupling techniques

Optimization of water and fertilizer coupling management approaches could not only increase apple yield and quality,but also reduce the potential negative impacts of such management activities on the environment.The aim of the present study was to determine the optimal water-nitrogen(WN)coupling management strategy in an apple orchard in the Weibei Dryland,Shaanxi Province,China,under limited irrigation.A randomized complete block design was adopted to test the effects of three drip irrigation levels(W1,300 m^(3)/hm^(2);W2,600 m^(3)/hm^(2);W3,900 m^(3)/hm^(2))and four N application levels(N0,0 kg/hm^(2);N1,200 kg/hm^(2);N2,400 kg/hm^(2);and N3,600 kg/hm^(2))on N distribution in the 0-100 cm soil profile.Apple yield and economic benefits under different treatments were also evaluated over a three-year period(2012-2014).Compared with the N0W1 treatment,soil N contents were higher and exhibited distinct trends in the soil profile under other treatments.Overall,total N contents exhibited a downward trend from the surface to the subsurface layers(0.11-2.34 g/kg);however,the total N contents of the lower soil layer increased with an increase in irrigation amount.NO_(3)-N contents were the lowest in the 40-60 cm soil layer and then increased with an increase in soil depth.The highest NO_(3)-N contents of different soil layers were observed under the N3W3 treatment,ranging from 124.7 mg/kg(0-20 cm)to 90.9 mg/kg(80-100 cm).NH_(4)^(+)-N contents were low(<10 mg/kg),mainly accumulating in the surface layer and decreasing toward the deeper layers>20 cm.Different water-N coupling treatments also increased apple yield by 7.30%-41.62%when compared with the N0W1 treatment.The highest apple yield(three-year mean:41.01 t/hm^(2))was observed under the N2W2 treatment,with an output value of 237900 RMB yuan/hm^(2) and a net income of 232000 RMB yuan/hm^(2).Considering fruit yield,partial productivity of N fertilizer,and economic and environmental benefits,the N2W2 treatment is the optimal water-N fertilizer coupling drip irrigation scheme for apple production in the study area and other similar dryland areas.

Assessing non-point source pollution in an apple-dominant basin and associated best fertilizer management based on SWAT modeling

Investigating the impact of apple-dominated areas on nitrogen(N)and phosphorus(P)losses at a basin scale was essential for the sustainable development of apple industry in China.This study conducted a survey on fertilizer application and built a Soil and Water Assessment Tool(SWAT)model to quantita-tively analyze the N and P losses in the Qixia apple-dominated area.Additionally,the decreases in N and P losses through adjusting the fertilizer application modes were evaluated.Results showed that average N and P losses in the Wulong River Basin(WRB)were 44.4 and 0.365 kg ha^(-1)in 2011-2017,respectively,and apple orchards accounted for 733%and 51.4%of the total N and P losses in the basin.Under nine fertilizer scheduling scenarios,three fertilizer schedule scenarios,automatic fertilizer application(S-AUTO),"one shot"mode(S1),and regulated fertilizer application(S-BSD),had the lowest N and P losses in apple orchards.The decreases in N loss ranged from 20.6%to 26.1%at the subbasin scale and 14.8%-30.7%at the basin outlet when applying the S-AUTO,S1,and S-BSD fertilizer application modes in Qixia apple orchards and all apple orchards in the WRB.The reductions in P loss varied from 22.0%to 46.1%at the subbasin scale and 14.6%-25.6%at the basin outlet.In orchard-dominated basin,N and P losses can be effectively reduced by optimizing the orchard fertilizer scheduling strategies.