Jingsheng Sun

Drip Irrigation Scheduling for Tomato Grown in Solar Greenhouse Based on Pan Evaporation in North China Plain

This study has investigated the suitable drip irrigation scheduling for tomato grown in solar greenhouse based on 20-cm pan evaporation (Epan) in North China Plain. Irrigation treatments included three irrigation frequencies (I1 10, I2 20 and I3 30 mm, and irrigation interval of 2–6 d for I1, 4–9 d for I2 and 8–12 d for I3) based on accumulated pan evaporation (Epan), and four plant-pan coefficients (Kcp1 0.5, Kcp2 0.7, Kcp3 0.9 and Kcp4 1.1). Results indicate that total irrigation amount, seasonal crop evapotranspiration (ET) and tomato yield (Y) were 185.1-365.8 mm, 249.1–388.0 mm and 99.6–151.8 t ha−1, respectively. Irrigation frequency and amount increased the yield, and second-degree polynomial relationship was found between Y and ET (R2=0.8671). Irrigation frequency did not increase mean fruit weight, diameter and length significantly but increased fruit number, total soluble solids content (TSS), TSS yield, fruit firmness and water use efficiency (WUE) and irrigation WUE (IWUE) significantly. Irrigation amount increased external quality of tomato but reduced TSS content, TSS yield, fruit firmness, WUE and IWUE significantly. Kcp3 and Kcp4 treatments had the highest fruit yield, but Kcp2 and Kcp3 treatments had the highest WUE. I1Kcp3 treatment (irrigation interval of 2–6 d, and Kcp=0.9) had higher IWUE, WUE, external quality, yield, and TSS yield, so it is recommended as the suitable irrigation scheduling for tomato grown in solar greenhouse in North China Plain.

Soil Salt Accumulation and Crop Yield under Long-Term Irrigation with Saline Water

AbstractAn experiment has been conducted to investigate the salt evolution process in soil and the response of crops to continuous irrigation with saline water under no artificial drainage from 2006 to 2013. A total of five salinity levels of saline water included 1.3, 3.4, 7.1, 10.6, and 14.1  dS/m, denoted as F1, F2, F3, F4, and F5. Results indicate that salt accumulation was significantly accelerated with the increased ratio of irrigation amount to precipitation (I/P), which was caused by higher annual irrigation times and irrigation quota, but soil salinity was reduced with the decline of I/P. Compared with initial soil salinity in 2006, final soil salinity in 2013 was decreased by 8.7 and 10.1% in the F1 and F2 treatments, but was increased by 7.3, 24.5, and 65.2% in the F3, F4, and F5 treatments. The peak salt values in the soil profile demonstrated a tendency to move up with the increasing salinity of irrigation water, suggesting that salt accumulated more readily in higher salinity treatments. Cot...

Dynamics of root water uptake and water use efficiency under alternate partial root-zone irrigation

AbstractThe distribution of root length density of maize in ridge culture under alternate partial root-zone furrow irrigation (APFI) and conventional furrow irrigation (CFI) was investigated, and two-dimensional models of root length density and root uptake were developed to investigate the water use efficiencies under different furrow irrigation modes. Results indicated that APFI increased root depth and horizontal extended distance of maize, as well as water use efficiency (WUE). Values of the mean absolute error (MAE), the root mean square error (RMSE), and the index of agreement (di) between measured and simulated values of root length density of maize under APFI ranged from 0.26 to 0.68, 0.03 to 1.51, and 0.64 to 0.85 cm m−3, respectively; and the coefficient of determination (R2) was greater than 0.80. Values of MAE, RMSE, and di between measured and simulated values of root length density of maize under CFI ranged from 0.01 to 0.26, 0.01 to 0.60, and 0.61 to 0.96 cm m−3, respectively; and R2 was hi...

A proposed surface resistance model for the Penman-Monteith formula to estimate evapotranspiration in a solar greenhouse

Greenhousing is a technique to bridge season gap in vegetable production and has been widely used worldwide. Calculation of water requirement of crops grown in greenhouse and determination of their irrigation schedules in arid and semi-arid regions are essential for greenhouse maintenance and have thus attracted increased attention over the past decades. The most common method used in the literature to estimate crop evapotranspiration (ET) is the Penman-Monteith (PM) formula. When applied to greenhouse, however, it often uses canopy resistance instead of surface resistance. It is understood that the surface resistance in greenhouse is the result of a combined effect of canopy restriction and soil-surface restriction to water vapor flow, and the relative dominance of one restriction over another depends on crop canopy. In this paper, we developed a surface resistance model in a way similar to two parallel resistances in an electrical circuit to account for both restrictions. Also, considering that wind speed in greenhouse is normally rather small, we compared three methods available in the literature to calculate the aerodynamic resistance, which are the ra1 method proposed by Perrier (1975a, b), the ra2 method proposed by Thom and Oliver (1977), and the ra3 method proposed by Zhang and Lemeu (1992). We validated the model against ET of tomatoes in a greenhouse measured from sap flow system combined with micro-lysimeter in 2015 and with weighing lysimeter in 2016. The results showed that the proposed surface resistance model improved the accuracy of the PM model, especially when the leaf area index was low and the greenhouse was being irrigated. We also found that the aerodynamic resistance calculated from the ra1 and ra3 methods is applicable to the greenhouse although the latter is slightly more accurate than the former. The proposed surface resistance model, together with the ra3 method for aerodynamic resistance, offers an improved approach to estimate ET in greenhouse using the PM formula.

Yield Response of Spring Maize to Inter-Row Subsoiling and Soil Water Deficit in Northern China

Background Long-term tillage has been shown to induce water stress episode during crop growth period due to low water retention capacity. It is unclear whether integrated water conservation tillage systems, such asspringdeepinter-row subsoiling with annual or biennial repetitions, can be developed to alleviate this issue while improve crop productivity. Methods Experimentswere carried out in a spring maize cropping system on Calcaric-fluvicCambisolsatJiaozuoexperimentstation, northern China, in 2009 to 2014. Effects of threesubsoiling depths (i.e., 30 cm, 40 cm, and 50 cm) in combination with annual and biennial repetitionswasdetermined in two single-years (i.e., 2012 and 2014)againstthe conventional tillage. The objectives were to investigateyield response to subsoiling depths and soil water deficit(SWD), and to identify the most effective subsoiling treatment using a systematic assessment. Results Annualsubsoiling to 50 cm (AS-50) increased soil water storage (SWS, mm) by an average of8% in 0–20 cm soil depth, 19% in 20–80 cm depth, and 10% in 80–120 cm depth, followed by AS-40 and BS-50, whereas AS-30 and BS-30 showed much less effects in increasing SWS across the 0–120 cm soil profile, compared to the CK. AS-50 significantly reduced soil water deficit (SWD, mm) by an average of123% during sowing to jointing, 318% during jointing to filling, and 221% during filling to maturity, compared to the CK, followed by AS-40 and BS-50. An integrated effect on increasing SWS and reducing SWD helped AS-50 boost grain yield by an average of 31% and biomass yield by 30%, compared to the CK. A power function for subsoiling depth and a negative linear function for SWD were used to fit the measured yields, showing the deepest subsoiling depth (50 cm) with the lowest SWD contributed to the highest yield. Systematic assessment showed that AS-50 received the highest evaluation index (0.69 out of 1.0) among all treatments. Conclusion Deepinter-row subsoilingwith annual repetition significantly boosts yield by alleviating SWD in critical growth period and increasing SWS in 20–80 cm soil depth. The results allow us to conclude that AS-50 can be adopted as an effective approach to increase crop productivity, alleviate water stress, and improve soil water availability for spring maize in northern China.

Water-Saving Irrigation Management and Decision Support System Based on WEBGIS

To improve the management of irrigation district is a key to develop water-saving agriculture. Based on the basic principles of water-saving irrigation, and using the method of Modified Penman Monteith and water balance equation, The system of irrigation management and decision support based on WEBGIS was developed, which is according to the soil moisture, crop growth status, meteorology change and the physiological and ecological index of crop that is monitored, and the situation of water supply and crop water-saving irrigation system were also combined with the system. With the help of the GIS, the system under discussion can predict the water requirement of the irrigation district so as to optimize the allocation of the water resources, to provide a decision support for irrigation managers, and to finally realize desirable irrigation practice. Besides, it will promote the automation, informationization, and intelligent of the irrigation district management.