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【Objective】 Reference crop evapotranspiration (ET0) is a critical parameter for irrigation and water management. This paper proposes a method for real-time forecasting ET0 using weather forecast data and a deep learning approach. 【Method】 The study was conducted in Xiaoshan District, Hangzhou City, Zhejiang Province. Hourly measured weather data and 1-7 day forecasted weather data from April 24, 2021 to December 31, 2023 were used as the dataset. The forecasting accuracy of the weather data was analyzed. A deep learning model based on the backpropagation (BP) neural network algorithm was developed and deployed for online training using Alibaba Cloud servers. 【Result】 The accuracy of the input parameters was generally reliable, with minimum temperature forecasts being more accurate than maximum temperature forecasts. Forecasting accuracy decreased as the lead time increased. Errors were observed in forecasting weather types and wind scales. The ET0 predicted by the model closely matched those calculated using real-time data, demonstrating high forecasting accuracy. During the training period, the model achieved a maximum accuracy of 91.56%, with an average root mean square error (RMSE) of 0.828 mm/day and a mean absolute error (MAE) of 0.667 mm/day. During the testing period, the model achieved an accuracy of 84.75%, with the average RMSE and MAE being 1.049 mm/day and 0.829 mm/day, respectively. 【Conclusion】 By using publicly accessible weather forecast data and an online-trained BP neural network model, real-time ET0 forecast can be achieved with high accuracy. This approach offers valuable support for farmers, enabling informed and timely irrigation decisions.

【Objective】 Garlic is a cash crop in Dali, but its irrigation with livestock wastewater risks environmental pollution. This paper studies the combined effect of livestock wastewater irrigation and nitrogen fertilization on growth, yield, water and nitrogen utilization efficiency of garlic, as well as soil nitrogen in attempts to screen a sustainable livestock wastewater irrigation schedule for garlic production in this region. 【Method】 The experiment was conducted at the National Agricultural Environmental Dali Observation and Experimental Station. There were five treatments: freshwater irrigation without nitrogen application (CK), freshwater irrigation with 390 kg/hm2 of nitrogen application (C1), freshwater irrigation with 312 kg/hm2 of nitrogen application (C2), livestock wastewater irrigation without nitrogen application (R1), livestock wastewater irrigation with 150 kg/hm2 of nitrogen application (R2). In each treatment, we measured the growth indexes, including dry weight, height, stem diameter and leaf area index of the garlic at different growing stages, as well as yield, and water and nitrogen use efficiency of the garlic and soil nitrogen content. 【Result】 The growth of the garlic was the best in R2, but was comparable with that in R1 and C1; R2 gave the highest yield. Compared to CK, C1, C2, R1 and R2 increased the bulb yield by 111.30%, 81.23%, 98.19%, and 142.01%, respectively. The nitrogen absorption and use efficiency of R1 and R2 was 154.71% and 92.25% higher than that of C1, respectively; the nitrogen partial factor productivity of R1 and R2 was 110.75% and 47.63% higher than that of C1, respectively. Compared to C1, R1 reduced the irrigation water productivity and soil nitrogen in the 0-40 cm of soil layer by 29.19%, while R2 increased the irrigation water productivity by 2.34% and reduced soil nitrogen in the 0-40 cm of soil by 3.89%, respectively. Compared to C1, R1 and R2 increased nitrogen in the 0-20 cm of soil layer by 170.90% and 255.93% respectively. 【Conclusion】 Livestock wastewater irrigation combined with appropriate base nitrogen fertilization can sustain garlic growth and yield. Livestock wastewater irrigation improved the nitrogen use efficiency and nitrogen partial factor productivity, with limited effect on average soil total nitrogen.

【Objective】Cultivation of sweet corn has increased over the past decades in some areas of China, but its demand for water and the associated irrigation strategies are poorly documented. The objective of this paper is to plug this knowledge gap. 【Method】A two-year field experiment designed based on the principle of achieving high yield was conducted. During the experiment we measured the change in soil moisture and meteorological factors, and used them to calculate water requirement, water consumption and crop coefficient (kc) of the crops. These help us to optimize the irrigation strategy for sweet corn production. 【Result】The water requirement, daily water consumption during the growth season of the sweet corn in 2016 and 2017 were 197.7 and 212.9 mm, 3.0 mm/d and 3.1 mm/d respectively. The daily water consumption varied with growth stage, being highest in the tasseling stage and least in the seedling stage. The average crop coefficient in 2016 and 2017 was 0.63 and 0.67, respectively, and the optimal calculation showed that changing irrigations times to four could reduce irrigation water by 31.84% to 33.97% compared to the currently used irrigation strategy. 【Conclusion】Water requirement of the sweet maize was low and its water consumption was similar to normal corn. Appropriate irrigation is essential to safeguarding its production.

Fertilization was an essential agricultural practice to improve soil fertility and quality, and the change leaf area index (LAI) and plant chlorophyll content, and had a direct effect on photosynthetic carbon assimilation and grain yield. In order to reveal the effect of a nitrogen~phosphorus fertilizer regulation and the ploughing down of Chinese milk vetch planted in the winter on the canopy characteristics and yield of early season rice, experiments were carried out, with 7 nitrogen levels (including 2 combined applications of chemical nitrogen and green manure levels) and 3 phosphorus levels and 2 No~nitrogen / phosphorous levels. LAI, the transmission characteristics of canopy photosynthetically active radiation (PAR), and leaf SPAD values were measured during the whole growth period, and the leaf net photosynthetic rate (Pn) was also measured in the heading~flowering period and in the grain~filling period, and the yield of early season rice was measured after harvesting. The results showed that nitrogen and phosphorus fertilizer could significantly affect the LAI which had a direct effect on light transmission and interception, SPAD value, Pn, and yield. In a certain range, increasing nitrogen fertilizer could cause a higher LAI, significantly, while increasing phosphorous fertilizer also changed the LAI in a slightly elevated but not significant manner. The variation trend of the canopy PAR interception and the LAI were basically the same, while the canopy PAR transmittance was the opposite. However, the effect of the LAI on reflectance was not obvious enough, its values, greatly influenced by mirror reflection, maintained between 3%~5%. With an increase of chemical fertilizer, the marginal diminishing effect gradually came into play. When the chemical fertilizer was overdosed, especially when the nitrogen fertilizer was higher than 225 kg/hm2 or the phosphate fertilizer higher than 120 kg/hm2, the effect curve appeared at an inflection point, and the early season rice growth might be inhibited and the grain yield would be cut. Ploughing down of moderate green manure (Chinese milk vetch) planted in the winter could significantly promote the LAI, light transmission, and interception, SPAD, photosynthesis, and yield under the same fertilizer, especially in the condition of low nitrogen. This could be because ploughing down green manure could increase the soil organic matter, soil humus, and soil microbial quantity and activity, and effectively reduce the fixation on nutrients. Available nutrients were released in spurts, and the soil nitrogen update was accelerated. An adequate soil nitrogen supply was conducive to maintaining the chlorophyll content of flag leaves, prolonging the functional period of leaves, and improving the photosynthesis efficiency and yield. The effects of a phosphorus deficiency on leaves were significantly less than that of low nitrogen availability, although phosphorus was limited to the promotion of chlorophyll content. A reasonable increase of phosphorus fertilizer could affect crop yield by promoting the LAI, light interception, and photosynthesis efficiency. This study considered that, in the Ganzhou and Fuzhou Plain Irrigation District, a combined application of 187.5~225 kg/hm2 nitrogen, 60~120 kg/hm2 phosphorus, and 15000 kg/hm2 Chinese milk vetch effectively improved the LAI, canopy PAR interception, and the content of chlorophyll, maintained a higher net photosynthesis efficiency, and consequently, enriched crop yield. It should be pointed out that, because of the limited manpower and material resources, this paper involved only one rice variety and one year's data, and the research on photosynthesis was only limited to the leaf scale, and in the measurement of PAR transmission characteristics and photosynthesis there existed a certain time lapse. Further studies are required to research the effect of different amounts of ploughing down of Chinese milk vetch on early season rice canopy characteristics. [ABSTRACT FROM AUTHOR]