[Effects of short-chain polyphosphate fertilization on inorganic P transformation and mobilization of Fe, Mn and Zn in soils.] / çŸ­é“¾èšç£·é ¸ç£·è‚¥å¯¹åœŸå£¤æ— æœºç£·è½¬åŒ–åŠé“é”°é”Œæœ‰æ•ˆæ€§çš„å½±å“.

Understanding the transformation of P in polyphosphate form in the soil and its effect on P availability is the prerequisite for reasonable polyphosphate fertilizer application. A pot experiment was conducted to explore the effects of polyphosphate fertilizers and MAP on soil available-P, inorganic P transformation in soils, soil micro-nutrient availabilities of Fe, Mn and Zn. Meanwhile, the effects of different P fertilizer on rape P nutrition and PUE in both calcareous and acid soils were investigated. Compared with the MAP treatment, polyphosphate fertilizers significantly increased plant available P concentrations in calcareous soil. Soil water soluble-P and Olsen-P were increased by 19.0% and 25.4%, respectively, and soil resin-P and NaHCO3-P (high labile P) and NaOH-P (medium labile P) increased by 22.8%, 43.3% and 33.8%, respectively. Those results implied that polyphosphate could reduce the fixation of P in calcareous soil. However, there was no significant effect of polyphosphate fertilization on improving P availability and reducing P fixation in acid soil. In comparison with MAP treatment, polyphosphate treatments significantly mobilized micronutrient in soils and increased the uptake of Fe, Mn and Zn by rape plants. In the calcareous soil, the available Fe, Mn, and Zn increased by 2.1%, 16.2% and 20.8%, respectively. In acid soil, the available Fe, Mn, and Zn increased by 6.6%, 11.9% and 9.2%, respectively. In addition, polypho-sphate treatments significantly increased dry mass, P uptake concentrations and P use efficiency (PUE) of rape in calcareous soil, but not in acid soil. In conclusion, polyphosphate fertilizer could significantly increase P availability and micronutrient availability, plant P nutrition and PUE, especially in calcareous soil. Thus, polyphosphate could be used as alternative of P source substituting the orthophosphate-based P fertilizer in calcareous soil.

[Effect of mineral N fertilizer reduction and organic fertilizer substitution on soil biological properties and aggregate characteristics in drip-irrigated cotton field.] / å‡æ°®é æ–½æœ‰æœºè‚¥å¯¹æ»´çŒæ£‰ç”°åœŸå£¤ç”Ÿç‰©å­¦æ€§çŠ¶ä¸Žå›¢èšä½“ç‰¹æ€§çš„å½±å“.

A four year field study was conducted to determine how soil biological properties and soil aggregate stability changed when organic fertilizer and biofertilizer were used to reduce chemical fertilizer application to a drip irrigated cotton field. The study consisted of six fertilization treatments: unfertilized (CK); chemical fertilizer (CF, 300 kg N·hm-2; 90 kg P2O5 · hm-2, 60 kg K2 O·hm-2); 80% CF plus 3000 kg·hm-2organic fertilizer (80%CF+OF); 60% CF plus 6000 kg·hm-2organic fertilizer (60%CF+OF); 80% CF plus 3000 kg·hm-2biofertilizer (80%CF+BF); and 60% CF plus 6000 kg·hm-2biofertilizer (60%CF+BF). The relationships among soil organic C, soil biological properties, and soil aggregate size distribution were determined. The results showed that organic fertilizer and biofertilizer both significantly increased soil enzyme activities. Compared with CF, the biofertilizer treatments increased urease activity by 55.6%-84.0%, alkaline phosphatise activity by 53.1%-74.0%, invertase activity by 15.1%-38.0%, ß-glucosidase activity by 38.2%-68.0%, polyphenoloxidase activity by 29.6%-52.0%, and arylsulfatase activity by 35.4%-58.9%. Soil enzyme activity increased as the amount of organic fertilizer and biofertilizer increased (i.e., 60%CF+OF > 80%CF+OF, 60%CF+BF > 80%CF+BF). Soil basal respiration decreased significantly in the order BF > OF > CF > CK. Soil microbial biomass C and N were 22.3% and 43.5% greater, respectively, in 60%CF+BF than in CF. The microbial biomass C:N was significantly lower in 60%CF+BF than in CF. The organic fertilizer and the biofertilizer both improved soil aggregate structure. Soil mass in the >0.25 mm fraction was 7.1% greater in 80%CF+OF and 8.0% greater in (60%CF+OF) than in CF. The geometric mean diameter was 9.2% greater in 80%CF+BF than in 80%CF+OF. Redundancy analysis and cluster analysis both demonstrated that soil aggregate structure and biological activities increased when organic fertilizer and biofertilizer were used to reduce chemical fertilizer application. In conclusion, the organic fertilizer and the biofertilizer significantly increased SOC, soil enzyme activity, and soil microbial biomass C and N. The organic fertilizers also improved soil aggregation. Therefore, soil quality could be improved by using these fertilizers to reduce chemical fertilizer application, especially under drip-irrigation.

[Effects of different cropping patterns on soil enzyme activities and soil microbial community diversity in oasis farmland].

Effects of long-term cropping patterns on the activities of peroxidase, invertase, arylsulfatase, dehydrogenase and protease were investigated in this paper. Four long-term cropping patterns included (1) 10 years continuous cropping of corn, (2) 8 years continuous cropping of wheat followed by 10 years continuous cropping of cotton, (3) 15 years continuous cropping of cotton, and (4) 6 years continuous cropping of cotton followed by 6 years of wheat/sunflower rotation. The responses of soil bacteria, fungi, ammonia oxidizing bacteria (AOB) , and the ammonia oxidizing archaea (AOA) to different copping patterns were analyzed. The results showed that cropping patterns significantly affected the activities of soil peroxidase, arylsulfatase, dehydrogenase and protease, while had no significant effect on soil invertase activity. The cropping patterns significantly influenced the diversity index of AOA, but had no significant influence on that of soil bacteria, fungi and AOB. The community structures of soil fungi and AOB were more sensitive to cropping patterns than soil bacteria and AOA. In conclusion, long-term continuous cropping of cotton decreased the activities of soil enzymes activities and soil microbial diversity in oasis farmland, while crop rotation could alleviate the negative influence.

[Response of water coupling with N supply on maize nitrogen uptake, water and N use effi- ciency, and yield in drip irrigation condition].

Water and nitrogen are two major limiting factors for upland crop growth and development in arid region. Optimizing regulation irrigation schedule, rates and coupling with N fertigation is an effective way for realizing crop production improvement as well as water and nutrient use efficiency enhancement. In the present study, a field trial was carried out to study the influence of water (4500, 6750, 9000 m³ · hm⁻²) coupling with N (0, 225, 330, 435, 540 kg · hm⁻²) supply on maize dry matter accumulation, N uptake, yield and nitrogen fertilizer use efficiency in drip irrigated high cultivated density (≥ 105000 plant · hm⁻²) condition. There was an obvious tendency that the amounts of corn dry matter accumulated and plant N absorbed increased with levels of water and N supply, however, those decreased gradually when the N applied rate beyond 435 kg · hm⁻² and irrigation level above 9000 m³ · hm⁻². For instance, the effect of irrigation level on corn dry matter accumulation order exhibited W6750 (36359 kg · hm⁻²) > W9000 (35077 kg · hm⁻²) > W45°° (33451 kg · hm⁻²), the sequence of amount of N absorbed showed N435 (462.0 kg · hm⁻²)> N540 (459.4 kg · hm⁻²) > N330 (423.4 kg · hm⁻²) > N225 (348.1 kg · hm⁻²), the amount of N absorbed in N435 treatment increased by 9.1% and 32.7%, respectively, in contrast with treatments of N330 and N220, whereas, the amount of N absorbed in N540 decreased by 0.6% than that in N435 treatment. The highest N absorption rate increased with N application rate increasing within N supply range of 0-435 kg · hm⁻², it reached peak value of 6.57 kg · hm⁻² · d⁻¹ at N application rate of 435 kg · hm⁻²,then had decline trend with increasing N rate. Both irrigation and N supply exerted a significant role on maize yield as well as yield component of kernel number per spike and kernel mass per spike. An obvious positive interaction was obtained between water and nitrogen, moreover, the effect of N on yield was substantially higher than that of irrigation. N fertilizer use efficiency increased with increasing N level within N supply range of 0-435 kg · hm⁻² and then dropped markedly when N rate above 435 kg · hm⁻² It was found that the water productivity of irrigation (WP i increased with increasing N level, while, that decreased with increasing irrigation rate. At the suitable irrigation range of 4500-6750 m³ · m⁻² the WP of 2.57-3.80 kg · m⁻³could be achieved. The maximum corn yield of 18072 kg · hm⁻² as reached at N rate of 567.0 kg · hm⁻² The best N rate of 427.9-467.7 kg N · hm⁻² btained the optimum yield of 17109-17138 kg · hm⁻² with the nitrogen partial factor productivity of 122 kg N · hm²and nitrogen use efficiency of 45.0% reached. In sum, optimizing water coupling with N supply was the effective strategy for realizing corn yield improvement as well as resources of water and N use efficiency in drip irrigation condition in arid region.

[Effects of brackish water irrigation on soil enzyme activity, soil CO2 flux and organic matter decomposition].

Brackish water irrigation utilization is an important way to alleviate water resource shortage in arid region. A field-plot experiment was set up to study the impact of the salinity level (0.31, 3.0 or 5.0 g · L(-1) NaCl) of irrigated water on activities of soil catalase, invertase, ß-glucosidase, cellulase and polyphenoloxidase in drip irrigation condition, and the responses of soil CO2 flux and organic matter decomposition were also determined by soil carbon dioxide flux instrument (LI-8100) and nylon net bag method. The results showed that in contrast with fresh water irrigation treatment (CK), the activities of invertase, ß-glucosidase and cellulase in the brackish water (3.0 g · L(-1)) irrigation treatment declined by 31.7%-32.4%, 29.7%-31.6%, 20.8%-24.3%, respectively, while soil polyphenoloxidase activity was obviously enhanced with increasing the salinity level of irrigated water. Compared to CK, polyphenoloxidase activity increased by 2.4% and 20.5%, respectively, in the brackish water and saline water irrigation treatments. Both soil microbial biomass carbon and microbial quotient decreased with increasing the salinity level, whereas, microbial metabolic quotient showed an increasing tendency with increasing the salinity level. Soil CO2 fluxes in the different treatments were in the order of CK (0.31 g · L(-1)) > brackish water irrigation (3.0 g · L(-1)) ≥ saline water irrigation (5.0 g · L(-1)). Moreover, CO2 flux from plastic film mulched soil was always much higher than that from no plastic film mulched soil, regardless the salinity of irrigated water. Compared with CK, soil CO2 fluxes in the saline water and brackish water treatments decreased by 29.8% and 28.2% respectively in the boll opening period. The decomposition of either cotton straw or alfalfa straw in the different treatments was in the sequence of CK (0.31 g · L(-1)) > brackish water irrigation (3.0 g · L(-1)) > saline water treatment (5.0 g · L(-1)). The organic matter decomposition rate in the plastic film mulched soil was significantly higher than that in the no plastic film mulched soil. 125 days after incubation, the recovery rates of cotton straw and alfalfa straw were 39.7% and 46.5% with saline water irrigation, 36.3% and 36.5% with brackish water irrigation, and 30.5% and 35.4% with CK, respectively. In conclusion, brackish water drip irrigation had a significant adverse effect on soil enzyme activities, which decreased soil microbial biomass, soil CO2 flux and soil organic matter decomposition, and subsequently deteriorated the soil biological characteristics in oasis farmland.