Mycorrhizal effects on crop yield and soil ecosystem functions in a long-term tillage and fertilization experiment.

It is well understood that agricultural management influences arbuscular mycorrhizal (AM) fungi, but there is controversy about whether farmers should manage for AM symbiosis. We assessed AM fungal communities colonizing wheat roots for three consecutive years in a long-term (> 14 yr) tillage and fertilization experiment. Relationships among mycorrhizas, crop performance, and soil ecosystem functions were quantified. Tillage, fertilizers and continuous monoculture all reduced AM fungal richness and shifted community composition toward dominance of a few ruderal taxa. Rhizophagus and Dominikia were depressed by tillage and/or fertilization, and their abundances as well as AM fungal richness correlated positively with soil aggregate stability and nutrient cycling functions across all or no-tilled samples. In the field, wheat yield was unrelated to AM fungal abundance and correlated negatively with AM fungal richness. In a complementary glasshouse study, wheat biomass was enhanced by soil inoculum from unfertilized, no-till plots while neutral to depressed growth was observed in wheat inoculated with soils from fertilized and conventionally tilled plots. This study demonstrates contrasting impacts of low-input and conventional agricultural practices on AM symbiosis and highlights the importance of considering both crop yield and soil ecosystem functions when managing mycorrhizas for more sustainable agroecosystems.

Occurrence of macroplastic debris in the long-term plastic film-mulched agricultural soil: A case study of Northwest China.

Widespread presence of plastic mulch has led to macroplastic (MaP) pollution. While this issue is widely explored in aquatic ecosystems, MaP pollution on land has been neglected. In 2019, we conducted a large-scale survey of MaPs in Northwest China in 0-30 cm soil with long-term mulching. Samples of MaP debris were collected from 67 sites across Gansu, east Qinghai, and north Shannxi Provinces. All visible MaP pieces for each site were separated and weighed. The mass of each MaP piece was calibrated by size measured in digital images. The MaP mass averaged 47.2 kg ha-1, and the number of MaPs averaged 266.2 pieces ha-1. The mass and number of MaPs varied from site to site. The mean size of MaPs was 19.5 cm2 piece-1 or 28.0 mg piece-1. More importantly, the number of small MaP pieces (<5 and 5-20 cm2 piece-1) accounted for 76.7% of the total number of MaPs detected, and small-sized plastic debris (<10 and 10-25 mg piece-1) were detected in 70.1% of the sampling sites. The percentage of small fragments increased before 15-year of mulching and then declined. However, the amount of medium-large debris (20-50 and >50 cm2 piece-1) showed a trend opposite to that of small fragments. The percentage of MaPs was greater in the small size group than in the medium-large size group. The arid to semi-arid area exhibited higher MaP contamination compared with the semi-arid to the semi-humid area. These observations indicate that plastic debris residing in soil tend to be fragmented, making plastic film recovery more challenging and causing severe soil pollution. Further studies are required to regulate plastic mulch methods and explore the degradation process.

Effects of plastic particles on germination and growth of soybean (Glycine max): A pot experiment under field condition.

Plastic residues have become a serious environmental problem in areas where agricultural plastic film are used intensively. Although numerous of studies have been done to assess its impacts on soil quality and crop yields, the understanding of meso-plastic particles effects on plant is still limited. In this study, low density polyethylene (PE) and biodegradable plastic (Bio) mulch film were selected to study the effects of meso-plastic debris on soybean germination and plant growth with the accumulation levels of 0%, 0.1%, 0.5% and 1% in soil (w: w, size ranging 0.5-2 cm) by a pot experiment under field condition. Results showed that the germination viability of soybean seeds was reduced to 82.39%, 39.44% and 26.06% in the treatments with 0.1%, 0.5% and 1% added plastic debris compared to the control (CK), respectively, suggesting that plastic residues in soil inhibit the viability of soybean seed germination. The plastic debris had a significant negative effect on plant height and culm diameter during the entire growth stage of soybean. Similarly, the leaf area at harvest was reduced by 1.97%, 6.86% and 11.53% compared to the CK in the treatments with 0.1%, 0.5% and 1% plastic debris addition, respectively. In addition, the total plant biomass under plastic addition was reduced in both the flowering and harvesting stages, compared to the CK. For the different type of plastic residues, plant height, leaf area and root/shoot ratio at group PE were significantly lower than those of groups treated by Bio. In conclusion, PE debris had a greater negative effects on plant height, culm diameter, leaf area and root/shoot ratio while Bio debris mainly showed the adverse effects on germination viability and root biomass especially at the flowering stage. Therefore, further research is required to elaborate plastic particles' effects on different stages of crops and soil quality.

Effects of plastic mulching on the accumulation and distribution of macro and micro plastics in soils of two farming systems in Northwest China.

BACKGROUND: Inappropriate disposal of the plastic mulching debris could create macroplastics (MaPs) and microplastics (MiPs) pollution in agricultural soil. METHODS: To study the effects of farming systems on accumulation and distribution of agricultural plastic debris, research was carried out on two farming systems in Northwest China. Farming in Wutong Village (S1) is characterized by small plots and low-intensity machine tillage while farming in Shihezi (S2) is characterized by large plots and high-intensity machine tillage. In September 2017, we selected six fields in S1, three fields with 6-8 years of continuous plastic mulching (CM) as well as three fields with over 30 years of intermittent mulching (IM). In S2, we selected five cotton fields with 6, 7, 8, 15 and 18 years of continuous mulching. In both regions, MaPs and MiPs from soil surface to 30 cm depth (0-30 cm) were sampled. RESULTS: The results showed that in S1, MaPs mass in fields with 6-8 years CM (i.e., 97.4kg·ha-1) were significantly higher than in fields with 30 years IM (i.e., 53.7 kg·ha-1). MaPs in size category of 10-50 cm2 accounted for 46.9% in fields of CM and 44.5% in fields of IM of total collected MaPs number. In S2, MaPs mass ranged from 43.5 kg·ha-1 to 148 kg·ha-1. MaPs in size category of 2-10 cm2 account for 41.1% of total collected MaPs number while 0.25-2 cm2 accounted for 40.6%. MiPs in S1 were mainly detected in fields with over 30 years of intermittent mulching (up to 2,200 particles·kg-1 soil), whereas in S2 were detected in all fields (up to 900 particles·kg-1 soil). The results indicated farming systems could substantially affect the accumulation and distribution of agricultural plastic debris. Continuous plastic mulching could accumulate higher amount of MaPs than intermittent plastic mulching. High-intensity machine tillage could lead to higher fragmentation of MaPs and more severe MiPs pollution. These results suggest that agricultural plastic regulations are needed.

The ideal harvest time for seeds of hybrid maize (Zea mays L.) XY335 and ZD958 produced in multiple environments.

To identify the ideal harvest time (IHT) for the seed production of XY335 and ZD958, six seed-related traits were evaluated in seeds harvested at 11 harvest stages in 8 environments. Standard germination (SG), accelerated aging germination (AAG) and cold test germination (CTG) were vigor traits; hundred-seed weight (HSW) and seed moisture content (SMC) were physiological traits; and ≥10 °C accumulated temperature from pollination to harvest (AT10ph) was an ecological trait. All the traits were significantly affected by harvest stage. The responses of SG, AAG, CTG and HSW to postponing harvest stage fit quadratic models, while SMC and AT10ph fit linear models. The IHT (indicated by the last date to reach maximum SG, AAG and CTG) were 57.97 DAP and 56.80 DAP for XY335 and ZD958, respectively. SMC and AT10ph at IHT were 33.15% and 1234 °C for XY335, and 34.98% and 1226 °C for ZD958, respectively. The period to reach the maximum HSW was 5 days later than the IHT. Compared to HSW and SMC, AT10ph had a closer relationship to the seed vigor traits. Together with the fact that AT10ph was less affected by environment, these results suggested that AT10ph may be a novel indicator for determining the IHT.

[Soil moisture dynamics of apple orchard in Loess Plateau dryland].

The soil moisture of 0-500 cm soil layer in a dryland orchard at its full fruit period was measured from 2009 to 2013 to explore the soil moisture dynamics. Results indicated that soil water consumption mainly occurred in the soil layer of 0-300 cm in normal rainfall year and below the 300 cm soil layer when the annual rainfall was less than 400 mm. The soil moisture in the 200-300 cm soil layer fluctuated most and was affected by rainfall and apple consumption. Seasonal drought usually happened between April and late June, while the accumulation of soil moisture mainly occurred in the rainy season from July to mid-October to alleviate the drought effectively in next spring.

Carbon accumulation in arid croplands of northwest China: pedogenic carbonate exceeding organic carbon.

Soil carbonate (SIC) exceeds organic carbon (SOC) greatly in arid lands, thus may be important for carbon sequestration. However, field data for quantifying carbonate accumulation have been lacking. This study aims to improve our understanding of SIC dynamics and its role in carbon sequestration. We analyzed two datasets of SOC and SIC and their (13)C compositions , one with over 100 soil samples collected recently from various land uses in the Yanqi Basin, Xinjiang, and the other with 18 archived soil samples from a long-term experiment (LTE) in Pingliang, Gansu. The data from the Yanqi Basin showed that SOC had a significant relationship with SIC and pedogenic carbonate (PIC); converting shrub land to cropland increased PIC stock by 5.2 kg C m(-2), which was 3.6 times of that in SOC stock. The data from the LTE showed greater accumulation of PIC (21-49 g C m(-2) year(-1)) than SOC (10-39 g C m(-2) year(-1)) over 0-20 cm. Our study points out that intensive cropping in the arid and semi-arid regions leads to an increase in both SOC and PIC. Increasing SOC through straw organic amendments enhances PIC accumulation in the arid cropland of northwestern China.

Microcalorimetric study of the effects of long-term fertilization on soil microbial activity in a wheat field on the Loess Plateau.

The effects of the long-term inorganic (nitrogen, N; phosphate, P) and organic (manure, M; straw, S) fertilizers/managemenet individually and in combinations (N, NP, SNP, M, and MNP) on soil microbial activity were investigated in a wheat field on the Loess Plateau, China. Microcalorimetry was used to determine microbial activity under different treatments. Nearly 30 years of consecutive fertilization has altered the culturable population of soil bacteria and fungi, the highest ones were detected in the treatments of manure and MNP, followed by the NP and SNP treatments. The microbial growth rate constant (µ/h(-1)) was significantly greater in the MNP treatment than all the other treatments. The total heat exchange values (Q/J) were the highest in the MNP and NP treatments, which were significantly different from the N and M treatments. The peak height (P(t)/µW) were significantly higher in MNP and NP treatments than in the remaining treatments. The peak time values (t(p)/h) among the MNP, NP, SNP and M, N and CK treatments were significantly different. In general, comparing with control, soil microbial activity was much higher in MNP, NP and SNP treatments, all including the phosphate fertilizer. Our results showed that the application of inorganic fertilizer and organic manure have positive effects on multiple soil chemical parameters, soil microorganism abundance and activity, and hence crop yield.

Long-term effects of fertilizer on soil enzymatic activity of wheat field soil in Loess Plateau, China.

The effects of long-term (29 years) fertilization on local agro-ecosystems in the Loess Plateau of northwest China, containing a single or combinations of inorganic (Nitrogen, N; Phosphate, P) and organic (Mature, M Straw, S) fertilizer, including N, NP, SNP, M, MNP, and a control. The soil enzymes, including dehydrogenase, urease, alkaline phosphatase, invertase and glomalin, were investigated in three physiological stages (Jointing, Dough, and Maturity) of wheat growth at three depths of the soil profile (0-15, 16-30, 31-45 cm). We found that the application of farmyard manure and straw produced the highest values of soil enzymatic activity, especially a balanced applied treatment of MNP. Enzymatic activity was lowest in the control. Values were generally highest at dough, followed by the jointing and maturity stages, and declined with soil profile depth. The activities of the enzymes investigated here are significantly correlated with each other and are correlated with soil nutrients, in particular with soil organic carbon. Our results suggest that a balanced application of fertilizer nutrients and organic manure (especially those containing P) has positive effects on multiple soil chemical parameters, which in turn enhances enzyme activity. We emphasize the role of organic manure in maintaining soil organic matter and promoting biological activity, as its application can result in a substantial increase in agricultural production and can be sustainable for many years.

[Effects of plastic film mulching and rain harvesting modes on chlorophyll fluorescence characteristics, yield and water use efficiency of dryland maize].

The differences on chlorophyll fluorescence parameters, yield and water use efficiency of dryland maize were compared among full plastic film mulching on double ridges and planting in catchment furrows (FFDRF), half plastic film mulching on double ridges and planting in catchment furrows (HFDRF), plastic film mulching on ridge and planting in film-side (FS), and flat planting with no plastic film mulching (NM) under field conditions in dry highland of Loess Plateau in 2007-2012. The results showed that fluorescence yield (Fo), the maximum fluorescence yield (Fm), light-adapted fluorescence yield when PS II reaction centers were totally open (F), light-adapted fluorescence yield when PS II reaction centers closed (Fm'), the maximal photochemical efficiency of PS II (Fv/Fm), the actual photochemical efficiency of PS II in the light (Phi PS II), the relative electron transport rate (ETR), photochemical quenching (qP) and non-photochemical quenching (qN) in maize leaves of FFDRF were higher than that of control (NM), and the value of 1-qP was lower than that of control, at 13:00, chlorophyll fluorescence parameters values of FFDRF was significantly higher than control, which were increased by 5.3%, 56.8%, 10.7%, 36.3%, 23.6%, 56.7%, 64.4%, 45.5%, 23.6% and -55.6%, respectively, compared with the control. Yield and water use efficiency of FFDRF were the highest in every year no matter dry year, normal year, humid year and hail disaster year. Average yield and water use efficiency of FFDRF were 12,650 kg x hm(-2) and 40.4 kg x mm(-1) x hm(-2) during 2007-2012, increased by 57.8% and 61.6% compared with the control, respectively, and also significantly higher compared with HFDRF and PS. Therefore, it was concluded that FFDRF had significantly increased the efficiency of light energy conversion and improved the production capacity of dryland maize.

[Effects of different tillage and fertilization modes on the soil physical and chemical properties and crop yield under winter wheat/spring corn rotation on dryland of east Gansu, Northwest China].

Based on the 7-year field experiment on the dryland of east Gansu of Northwest China in 2005-2011, this paper analyzed the variations of soil moisture content, bulk density, and nutrients content at harvest time of winter wheat and of the grain yield under no-tillage and conventional tillage and five fertilization modes, and approached the effects of different tillage and fertilization modes on the soil water storage and conservation, soil fertility, and grain yield under winter wheat/ spring corn rotation. In 2011, the soil moisture content in 0-200 cm layer and the soil bulk density and soil organic matter and available nitrogen and phosphorus contents in 0-20 cm and 20-40 cm layers under different fertilization modes were higher under no-tillage than under conventional tillage. Under the same tillage modes, the contents of soil organic matter and available nitrogen and available phosphorus were higher under the combined application of organic and inorganic fertilizers, as compared with other fertilization modes. The soil available potassium content under different tillage and fertilization modes decreased with years. The grain yield under conventional tillage was higher than that under no-tillage. Under the same tillage modes, the grain yield was the highest under the combined application of organic and inorganic fertilizers, and the lowest under no fertilization. In sum, no-tillage had the superiority than conventional tillage in improving the soil water storage and conservation and soil fertility, and the combined application of organic and inorganic fertilizers under conventional tillage could obtain the best grain yield.

Long-term effect of manure and fertilizer on soil organic carbon pools in dryland farming in northwest China.

An understanding of the dynamics of soil organic carbon (SOC) as affected by farming practices is imperative for maintaining soil productivity and mitigating global warming. The objectives of this study were to investigate the effects of long-term fertilization on SOC and SOC fractions for the whole soil profile (0-100 cm) in northwest China. The study was initiated in 1979 in Gansu, China and included six treatments: unfertilized control (CK), nitrogen fertilizer (N), nitrogen and phosphorus (P) fertilizers (NP), straw plus N and P fertilizers (NP+S), farmyard manure (FYM), and farmyard manure plus N and P fertilizers (NP+FYM). Results showed that SOC concentration in the 0-20 cm soil layer increased with time except in the CK and N treatments. Long-term fertilization significantly influenced SOC concentrations and storage to 60 cm depth. Below 60 cm, SOC concentrations and storages were statistically not significant between all treatments. The concentration of SOC at different depths in 0-60 cm soil profile was higher under NP+FYM follow by under NP+S, compared to under CK. The SOC storage in 0-60 cm in NP+FYM, NP+S, FYM and NP treatments were increased by 41.3%, 32.9%, 28.1% and 17.9%, respectively, as compared to the CK treatment. Organic manure plus inorganic fertilizer application also increased labile soil organic carbon pools in 0-60 cm depth. The average concentration of particulate organic carbon (POC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) in organic manure plus inorganic fertilizer treatments (NP+S and NP+FYM) in 0-60 cm depth were increased by 64.9-91.9%, 42.5-56.9%, and 74.7-99.4%, respectively, over the CK treatment. The POC, MBC and DOC concentrations increased linearly with increasing SOC content. These results indicate that long-term additions of organic manure have the most beneficial effects in building carbon pools among the investigated types of fertilization.

[Effects of rape cropping in summer fallow period on dryland soil moisture content and winter wheat yield].

Taking the fallow land with wheat stubble after harvesting as the control, a 4-year field experiment was conducted in a dryland of east Gansu, Northwest China to investigate the effects of rape cropping in summer fallow period on the soil moisture content, wheat yield, and water use efficiency (WUE). The rape was sown at 6 dates. There was a significant difference (P < 0.05) in the soil moisture content in summer fallow period when the rape was sown at different dates. When the rape was sown on August 5, the soil water storage efficiency was 58.5%, and the wheat yield and WUE were increased by 7.5% and 5.9%, respectively, as compared with the control. Averagely, cropping rape in fallow period could increase the wheat yield by 16. 1% in dry year and 6.8% in normal year. It was suggested that rape cropping in summer fallow period would benefit the wheat yield and drought resistance of drylands in Northwest China.

Breviscapine, a traditional Chinese medicine, alleviates myocardial ischaemia reperfusion injury in diabetic rats.

OBJECTIVE: The aim of this study was to explore the effects of breviscapine on the expressions of intercellular adhesion molecule-I (ICAM-I), ATPase activities and oxidative stress in ischaemia-reperfused (I/R) myocardium of diabetic rats. METHODS: Sprague Dawley rats were randomly divided into two groups (a diabetic group and a non-diabetic group), and each group divided into two subgroups including a control group and a breviscapine group. Reperfusion surgery was carried out in all rats.The contents of malonaldehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-P(x)) in serum and myocardial tissues were measured. The activities of Na(+)-K(+)-ATPase, Mg(2+)-ATPase, Ca(2+)-ATPase in myocardial mitochondria were measured. The ICAM-I protein expressions in myocardium were determined with the immunohistochemical method. RESULTS: The activities of Na(+)-K(+)-ATPase, Mg(2+)-ATPase, Ca(2+)-ATPase were significantly increased in diabetic rats in the breviscapine group compared with the control group. Compared with the non-diabetic control group, the contents of MDA in serum and myocardium were significantly increased in the diabetic control group. Breviscapine led to a reduction of the contents of MDA in the diabetic and non-diabetic group. Compared with the non-diabetic control group, the activities of SOD and GSH-P(x) in the myocardium were significantly decreased in the diabetic control group.The activities of SOD and GSH-P(x) in serum and myocardium were increased in the diabetic and non-diabetic group after breviscapine treatment. Compared with the non-diabetic control group, the ICAM- I protein expressions were increased significantly in the diabetic control group. Breviscapine decreased the ICAM-I protein expression in the diabetic and the non-diabetic group. CONCLUSION: Breviscapine may have protective effects on myocardial ischaemia reperfusion injury of diabetic rats by scavenging oxygen free radicals, decreasing the expressions of ICAM-I protein in myocardium and increasing the activities of Na(+)-K(+)-ATPase, Mg(2+)-ATPase, Ca(2+)-ATPase in myocardial mitochondria.