At present, there is a lack of understanding of the dynamic characteristics of the carbon, nitrogen, and enzyme activities of the soil microbial biomass of Panax notoginseng under irrigation and fertilization. We set up a field experiment with 3 irrigation and 4 fertilization levels for a total of 12 treatments plus a control in the micro-sprinkler Panax notoginseng farmland in Luxi County, Yunnan Province, from 2018 to 2020. The results showed that the soil microbial biomass carbon, nitrogen, and enzyme activities increased from the rooting period to the flowering period, and then decreased in the fruiting period.The soil microbial biomass carbon, nitrogen, and enzyme activities of Panax notoginseng reached the maximum values in the flowering period, while the minimum values were reached in the rooting period. There were significant positive correlations between the soil microbial biomass carbon and nitrogen and enzyme activities during different growth periods under different water and fertilizer optimization management. This study revealed the tendency of the carbon, nitrogen, and enzyme activities of the soil microbial biomass of Panax notoginseng with the growth periods. It also analyzed the optimal management of different water and fertilizer regimes and the Ci values of soil microbial biomass carbon, nitrogen, and enzyme activities in different growth periods to determine the best water and fertilizer treatment methods in each growth period through the entropy value method combined with the TOPSIS method. The study found that the Ci values changed with the change in the fertilization level under the same irrigation level. The Ci values decreased and then increased with increasing irrigation water under the same fertilization level. These results showed that, in terms of the effect of different water and fertilizer treatments on the regulation of the soil microbial biomass carbon, nitrogen, and enzyme activities in each growth period, the irrigation volume of 10 mm and fertilizer application of 8.00 kg.667− 1.m− 2 during the rooting period of Panax notoginseng were most effective, while an irrigation volume of 15 mm and fertilizer application of 8.00 kg.667− 1.m− 2 were more suitable for the seedling, flowering, and fruiting periods.
There is a lack of understanding of the dynamic characteristics of carbon, nitrogen, and enzyme activity of soil microbial load of Panax notoginseng in water-fertilizer intercrops. In this study , we reveal that different water and fertilizer regulations affect microbial biomass carbon, nitrogen, and enzyme activities. As the study object, we set up 3 irrigations,4 fertilization levels, and 1 control in micro-sprinkler irrigated Panax notoginseng farmland, Luxi County, Yunnan Province from 2018 to 2020. The findings demonstrated that under the same water and fertilizer management, the carbon, nitrogen, and enzyme activities of Panax notoginseng’s soil increased and then decreased with increasing fertility time, in descending order of flowering, fruiting, seedling, and rooting periods.. The maximum value is reached during the flowering period ,while the minimum value is reached during the rooting period. The soil microbial carbon and nitrogen contents ranged from 0.49 to 1.05 g.kg and from 14.98 to 66.21 mg.kg , respectively, and soil sucrose enzyme activity was the largest, ranging from 17.12 to 68.79 mg.kg .d. . The soil microbial carbon , nitrogen and enzyme activities of Panax notoginseng increased with the rate of water and fertilizer application under different water and fertilizer management. The soil microbial carbon , nitrogen and enzyme activities of Panax notoginseng at the flowering period were the largest. The soil microbial carbon and nitrogen activities of Panax notoginseng increased with the increase of irrigation and fertilizer application, whereas the soil microbial carbon and nitrogen activities of W3F4 increased by 0.41 g.kg and 39.52 mg.kg respectively compared with W1F1. Soil urease, sucrase, acid phosphatase, and catalase activities were the highest in W3F4, with increases of 44.26%, 61.51%, 42.56, and 32.25% respectively compared to W1F1. There was a significant positive correlation between soil microbiomass carbon and nitrogen and enzyme activity under different water and fertilizer management. Soil microbiomass carbon and nitrogen content determined soil enzyme activity. The entropy value method combined with the TOPSIS method was used to analyze the optimal program fit Ci of soil microbial biomass carbon, nitrogen, and enzyme activity under different water and fertilizer optimization management and at different fertility periods. The results showed that the Ci values were F4, F3, F2, and F1 in descending order under the same irrigation level treatment.The Ci values decreased and then increased with increasing irrigation water under the same fertilization level treatment. The carbon, nitrogen, and enzyme activities of the soil’s microbial biomass were successfully controlled when Panax notoginseng was treated with W2F4 during the rooting period and W3F4 during the seedling, flowering, and fruiting periods. This study is an essential guideline for water and fertilizer regulation of Panax notoginseng and its yield quality improvement.
To determine Calculation method of sprinklerand micro-sprinklers, computational models for sprinkler range model is constructed, based on hydraulic parameters of nozzle diameter, working pressure, Installation Heights, spray elevation angle, discharge coefficient, wind direction and speed, water flow regime, and water droplet motion in air, etc., as well by Newton's second law of motion, aerodynamics, and fluid mechanics principles, and by experimental verification for common sprinkler range, nozzle diameter, working pressure, spray elevation angle, Installation Heights, discharge coefficient, and wind direction and speed. The results indicate that sprinkler range with nozzle diameter, working pressure, Installation Heights, spray elevation angle, discharge coefficient, wind direction and speed, water flow regime, and droplet motion in air was in highly significant correlation, the sprinkler range Progressive decreases around the sprinkler along the sprinkler range direction, as well increases by 5.2342%~10.6278% in the downwind direction and decreases by 4.6897%~9.8623% in the headwind direction compared with no wind. The wind speed increases, then the range decreases, and the wind direction shifts, then the range shifts, so the wind direction wind speed changes then the range changes. The coefficients of determination, the consistency Index, the root mean square error, absolute error, relative error between calculated Values and Measured Values of computational models are 0.9146, 0.9205, 8.7748%, 10.4980%, 8.2524% and 8.1421%, respectively. The smaller coefficients of determination and the consistency Index of calculated Values and Measured Values of computational model under windy conditions comparing with no wind, as well the larger root error, deviation, absolute error and relative error. The calculation model in this paper has a clear principle, comprehensive influence factors, complete physical meaning, high calculation accuracy, small error, and wide applicability. This calculation model can effectively reflect the nozzle range change law. This study provides theoretical basis for determining the sprinkler hydraulic performance and provides technology support for Planning and Design of sprinkler irrigation system.
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