Application of Matter-element Model in Soil Nutrient Evaluation of Ecological Fragile Region

On the basis of the soil environment investigation in Da＇an City, Jilin Province, China, 40 soil samples from main land use types were obtained and tested by standard method. Soil organic matter （SOM）, total N （TN）, total P （TP）, total K （TK）, available N （AN）, available P （AP） and available K （AK） were chosen as the evaluation factors. A regional soil nutrient evaluation model was developed based on the matter-element model. The results show that the soil samples with nutrient grade Ⅱ-Ⅴ respectively account for 10%, 30%, 32.5% and 27.5%, and those with grade Ⅳ and Ⅴ account for 60% in all samples. The relationship between soil nutrients and land types indicates that the nutrients of farmland are relatively good, with 41.7% of soil samples with the nutrient grade Ⅳ and Ⅴ. The nutrients of saline-alkali land and sandy land are the worst, with 100% of soil samples with the nutrient grade IV and V. And the ratios of soil samples grade IV and V in grassland and wasteland are respectively 62.5 % and 54.55%. Generally speaking, the soil nutrients status in Da＇an City is poor, 60% of soil samples are in poor and extremely poor conditions, indicating that the soil has been severely eroded. Being a relatively superior evaluation method with more accurate resuits and spatial distribution consistency, matter-element analysis is more suitable for regional soil nutrient evaluation than previous models.

Study on Several Characteristics of Agaricus blazei MurrilStrain J_3 Irradiated by ^(60)Co

A new mutant strain J3 from Agaricus blazei Murril was obtained by 60Co irradiation. The yields of successive generations were increased more than 70% to compare with their original strain. The component analysis on amino acids and fatty acid illuminated that the nutrient value of strain J3 fruiting body was better than the original strain. The apparent nodule structure was found in the hyphea of J3 strain through the observation by scanning electron microscope. RAPD analysis showed the great difference of PCR fingerprints between J3 and its original strain. It is a promising mutant strain for further commercial development in the future.

A Device for Simulating Soil Nutrient Extraction and Plant Uptake

In situ evaluating the availability of soil nutrients has been a challenge. In this study, a new type of Device for Simulating Soil Nutrient Extraction and Plant Uptake （DSSNEPU） and its operating procedures were introduced. The device consists of a sampling tube, a fluid supply system, a low pressure system, a tube sheath and an elution cylinder. The sampling tube was firstly soaked in the solution of 0.5 mol L-1 NaHCO3 and then buried into soils. The fluid supply system was connected to the sampling tube and the deionized water was supplied. During the period, low pressure system started a vacuum for 3 min every 10 rain interval. After extraction, the sampling tube was removed and the nutrients on the sampling tube were eluted with 0.5 tool L-1 HCl. The elution solution was used for nutrient measurement. The amounts of P and K extracted by DSSNEPU reached the maximal values after 4 h. No significant increases of P and K were observed for longer extraction duration. The optimal temperature for extracting P and K was 30 ℃ in this experiment. Extracted P and K were increased by 83.3% and 84.6% with the employment of low pressure system in comparison to those without employing low pressure system. Correlation analysis indicated that 1~ and K extracted by DSSNEPU were highly correlated with those by conventional chemical extraction and by plant uptake. The above results suggest that this device is applicable to assess the availability of nutrients in soils.

Screening of the Optimal Potassium Fertilization Rate for Maximizing Bulb Yield and Potassium Nutrient Evaluation in Fritillaria thunbergii Miq.

Background:The dry bulb of Fritillaria thunbergii Miq.is a traditional Chinese medicine,and is the leading product of the geo-authentic crude drugs‘Zhebawei’in Zhejiang Province.Fritillaria thunbergii requires more potassium(K)than nitrogen and phosphorus,while the response of F.thunbergii to K has rarely been studied.Objective and Methods:To evaluate the K nutritional status of F.thunbergii,a 2-year field experiment was conducted under six K application rates(0,40,80,120,160,and 200 kg K_(2)O ha−1)with two F.thunbergii cultivars(ZB1,narrow-leaf;ZB2,broad-leaf).Results:The bulbus Fritillariae Thunbergii(BFT)yield increased to a plateau with more than~120 kg K_(2)O ha-1.The BFT quality met the standard of Pharmacopoeia of P.R.China with more than 40.0 kg K_(2)O ha^(-1).Leaf K concentration was significantly correlated with BFT yield,and was more sensitive to K application rate as compared to those of stems and flowers.Potassium application extended the duration of rapid leaf-biomass accumulation and increased the accumulation rate.Two cultivars had similar response patterns to K application,but ZB2 had higher K partial productivity,leaf-biomass,and leaf K concentration than ZB1.Conclusion:108.4-128.0 kg K_(2)O ha^(-1) was the optimal K application range for BFT yield.The potassium nutrition index(KNI)model established based on leaf K concentration has biological significance and can be used for dynamic diagnosis of K nutritional status of F.thunbergii with both accuracy and simplicity.