EM enrichment culture liquid was immobilized on nano-silica carrier to form microbial nano ball, so as to investigate the reaction kinetics of ammonia nitrogen (NH4+-N) by microbial nano ball. The results showed that first order reaction kinetics model could describe NH4+-N removal by different diameter microbial nano-silica balls well. And the microbe could keep higher biological activity between 0-72h. Reaction kinetic equations of NH4+-N were: (1) when diameter was 10mm, (0-48h), (48-72h); (2) when diameter was 20mm, (0-48h), (48-72h); (3) (0-48h), (48-72h).
Abstract The wear of backup rolls will have a great impact on the quality of hot rolled strip sheet shape. In order to overcome the limitations of the finite element method (FEM) in calculating the wear of backup rolls in terms of efficiency and accuracy, this paper proposes a FEM + ML tandem hybrid model to optimise the prediction effect of the finite element method (FEM) on the wear of backup rolls. Firstly, a backup roller wear model is established based on FEM. Secondly, in order to select the optimal machine learning (ML) algorithm as the finite element error compensation model, three types of finite element error compensation models were established based on the random forest (RF) algorithm, radial basis neural network (RBF) algorithm, and particle swarm optimisation support vector machine (PSO-SVM) algorithm. Finally, the three types of finite element error compensation models were connected in series with the FEM model to compare the prediction performance of the three types of FEM + ML models on the wear of backup rolls. The numerical experimental results show that the FEM + PSO-SVM model can predict the wear of the backup roll better, and the PSO-SVM algorithm is most suitable for establishing the finite element error compensation model. It is proved that the FEM + ML model proposed in this paper can effectively improve the accuracy and computational efficiency of the FEM model for predicting the wear of the backup rolls without adding microelements. In addition, among the hot rolling parameters, the rolling force has the greatest influence on the wear of the backup rolls, and excessive rolling force should be avoided for a single pass in order to slow down the wear of the backup rolls.
This paper studied the forms of inorganic phosphorus and organic phosphorus in 0~100 cm soil profiles after 23 year continuum application fertilizers by the methods of JiangGus, and BowmanColes, and researched the relationships among phosphorus forms by correlation analysis, path analysis and multiple regression analysis. The results showed that the importance of phosphorus, path coefficient, for available phosphorus in proper order is Ca2-P(0.8941)Ca8-P(0.1603) Al-P(-0.0683) O-P(-0.0297) Fe-P(0.0248) active organic P(0.0193)high stable organic P(-0.0187) medium stable organic P(-0.0178) medium active organic P(0.0077) Ca10-P(0.0029).The Ca2-P and Ca8-P are main source of available phosphorus by the results of multiple regression analysis.
Critical nutrient concentrations are required for assessing the level of crop nutrition. Our objectives were to validate an existing model of critical phosphorus concentration ( P c = 0.94 + 0.107 N ) in the shoot biomass (SB) of wheat ( Triticum aestivum L.) and to assess the alternative approach of expressing P c as a function of SB rather than shoot N concentration ( N ). We applied four rates of P fertilizer (0, 10, 20, and 30 kg P ha −1 ) on soils with a low to medium available P concentration at four locations in three countries (Normandin [Canada; 2010, 2011, 2012], Brandon [Canada; 2010, 2012], Ylistaro [Finland; 2010, 2011], and Beijing [China; 2012]) for a total of 8 site‐years. Shoot biomass, and N and P concentrations were measured on five dates with 1‐wk intervals from vegetative to late heading stages of development, and grain yield was measured. Increasing P fertilization did not increase grain yield at any of the 8 site‐years and had little effect on SB. Under nonlimiting P conditions achieved in most cases with no applied P, the allometric relationship between P c and SB differed among locations, while the relationship between P c and shoot N concentration ( P c = −0.677 + 0.221 N − 0.00292 N 2 , R 2 = 0.82, P < 0.001) was independent of locations. This model of critical P concentration predicts lower P c values than that previously reported, mostly for high shoot N concentrations. This predictive model of P c can be used to quantify the degree of P deficiency during the wheat growing season.
In an arid region, water shortage limits agricultural development, and worse, soil salinization is accompanied by soil moisture drought. In this region, hydraulic lift occurs due to the drying upper layer caused by high precipitation and the wet lower layer. Hydraulic lift is defined as water redistribution from wetter, deeper soil layers to drier, shallower soil layers near the soil surface through the plant roots. To examine the effects of water and salt stresses on tomato yield and fruit quality under the condition of hydraulic lift, a 2year experiment was conducted. Different water and salt treatments were designed, including three water levels (W1, W2 and W3 indicating soil moisture contents of 60%–70%, 50%–60% and 40%–50% of the field capacity, respectively) and four salt levels (S0, S1, S2 and S3 indicating NaCl addition of 0%, 0.2%, 0.4% and 0.6% of the dry soil weight, respectively) of the upper pot, and water and salt levels of control treatment (CK) were W1 and S0, respectively. The yield under other treatments significantly decreased by 4.59%–58.39% and 5.12%–62.96% in 2018 and 2019, respectively, compared with that under CK, and the yield under W1S1 treatment had no significance with that under CK in 2018. The firmest fruit quality was observed in the plant under W3S1 treatment, and the percentage increases were 28.67% and 28.89% in both years compared with that under CK. Water, salt stress and their interactions had significant effects on tomato taste quality and vitamin C. Tomato taste quality and vitamin C decreased under the W3 and S3 treatments. In both years, the total magnitudes of hydraulic lift during the entire growth period were higher under the W1S2 treatment (65.20% and 76.06%, respectively) than that under CK. Whereas yield and total magnitudes of hydraulic lift were significantly both correlated with single fruit weight, single fruit volume, fruit shape index and taste qualities, no correlations were observed between hydraulic lift and yield. Mild waterdeficit and salt stresses could improve tomato quality with negligible yield loss, and hydraulic lift had positive effects on fruit quality. Principal component analysis revealed that the combination of W1 and S1 treatments increased fruit quality and total hydraulic lift magnitudes with an acceptable yield decline. These results are important for tomato production in arid saline-alkali region where hydraulic lift is positively corelated with fruit quality and famers may consider this trait to resist drought and soil salinization. Future studies focusing on the effects of the internal mechanisms of hydraulic lift caused by changes in sap flow on tomato quality and yield are warranted.
Drought hardening could promote the development of plant roots, potentially improving the resistance of crops to other adversities. To investigate the response and resistance of physiological and growth characteristics induced by drought hardening to salt stress in the later stages, a greenhouse experiment was carried out from 2021 to 2022 with one blank control treatment and twelve treatments that comprised combinations of four irrigation regimes (W1 = 85%, W2 = 70%, W3 = 55%, and W4 = 40% of the field capacity) and three irrigation water salinity levels (S2, S4, and S6, referring to 2 g, 4 g, and 6 g of sodium chloride added to 1000 mL of tap water, respectively). The results show that saline water irrigation introduced a large amount of salt into the soil, resulting in the deterioration of tomato growth, physiology, yield, and water use efficiency (WUE), but had a positive, significant effect on fruit quality. When the irrigation water salinity was 2 g L−1, the W2 treatment could reduce soil salt accumulation, even at the end of the maturation stage; consequently, enhancing the increments in plant height and leaf area index during the whole growing stage. The physiological activity of tomato plants under the W2 and W3 treatments showed a promoting effect. Correspondingly, the maximum values of the fruit quality of tomato plants irrigated with the same saline water were all obtained with the W2 or W3 treatment. However, the yield and WUE of the W3 treatment were lower than that of the W2 treatment, which was the highest among the same saline water irrigation treatments, consistent with the reflection of the changing trend of the ratio of fresh weight to dry weight. Overall, drought hardening can be considered an economically viable approach to mitigate the hazards of saline water irrigation, and the W2S2 combination is recommended for tomato production due to the maximum values of yield and WUE with a higher fruit quality among the twelve saline water irrigation treatments.
The continuous airflow enclosures with an acid trap method was widely used to investigate ammonia (NH3) volatilization in field; however, it could be time-consuming for the estimation of NH3 volatilization in field with the application of controlled-release urea (CRU) because NH3 volatilization with CRU application could occur during the entire crop growth period. An NH3 volatilization estimation method based on the modified Jayaweera–Mikkelsen (J-M) model combined with the Sherlock–Goh model was used to simulate NH3 volatilization in a paddy field after 255 kg N ha−1 as CRU (polymer-coated urea with the concentration of 43% nitrogen, 100% for basal) and urea (70% for basal, 30% for topdressing) during the rice growth period including flooded and non-flooded periods in Wuxi, China. Results indicated that NH3 volatilization can be modeled with the proposed measure because no significant difference (P< 0.001) was observed between the simulated values and the observed values; the correlation coefficient (r2) was 0.615 for CRU and 0.840 for urea during the flooded period, and 0.991 for CRU and 0.946 for urea during the non-flooded period. Compared with urea, NH3 volatilization was minimized by 43.2% with the application of CRU based on simulated value within the rice growth period, which was 40.40 kg N ha−1 for CRU and 78.62 kg N ha−1 for urea during the flooded period, and 5.52 kg N ha−1 for CRU and 2.33 kg N ha−1 for urea during the non-flooded period. Therefore, CRU could be a promising nitrogen fertilizer to prevent NH3 losses in the rice paddies at the investigated area.
Biochar application is an effective way to improve soil organic carbon (SOC) content and ensure food security. However, there were differences in SOC content following biochar application under different conditions. We collected 637 paired comparisons from 101 articles to determine the following: (1) the average effect of biochar application on SOC content and (2) the response of SOC content to different soil nutrient contents, climate zones and cropping systems following biochar application. The results showed that the soil available phosphorus (P) content and soil available potassium (K) content reached the highest level in the category of <10 mg kg−1 and >150 mg kg−1, respectively. Soil total P content subgroups achieved maximum increase in the intermediate category. The Cw zone (temperate, without dry season) obtained the maximum level of SOC content. Compared with plough tillage, rotary tillage presented significantly higher SOC content. Therefore, low available P and K contents, moderate soil total N and P contents, rotary tillage and the Cw zone were more effective in increasing SOC content. Furthermore, the results of a random forest algorithm showed that soil nutrient contents were the most important variables. This study provided a scientific basis for SOC sequestration and improving soil fertility.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
