Effects of Soluble Organic Fertilizer Combined with Inorganic Fertilizer on Greenhouse Tomatoes with Different Irrigation Techniques

A reasonable fertilization rate and appropriate irrigation technology can lead to the green development of greenhouse tomatoes. The purpose of this study was to explore suitable irrigation technology for greenhouse tomatoes and the appropriate application rate of the soluble organic fertilizer and inorganic fertilizer combination. In 2021 and 2022, the effects of different irrigation techniques and fertilization treatments on tomato plant growth, fruit quality, yield, and efficiency were studied. The irrigation techniques in this study were drip and Moistube irrigation, and there were seven types of fertilization treatment, namely, no fertilization treatment (CK); low-volume (T1, 330 kg/hm2), medium-volume (T2, 660 kg/hm2), and high-volume inorganic fertilizer treatments (T3, 990 kg/hm2); and three inorganic fertilizer treatments of low-volume inorganic fertilizer (T1, 330 kg/hm2) combined with low-volume (F1, T1 + 75 kg/hm2), medium-volume (F2, T1 + 225 kg/hm2), and high-volume (F3, T1 + 375 kg/hm2) organic fertilizer. A total of 14 experimental treatments were implemented for irrigation and fertilization. The results of the two-year experiment show that the growth effect on the height, stem diameter, and leaf area index of tomato plants was the best using the treatment of low-concentration inorganic fertilizer combined with medium-concentration organic fertilizer with Moistube irrigation and drip irrigation. Using the two irrigation methods, the application of soluble organic fertilizer increased the yield and improved the fruit quality of the tomato. The maximum yield increased by 28.52%, the soluble sugar content increased by 14.49%, the vitamin C content increased by 45.04%, and the lycopene increased by 18.79%. The entropy-weight TOPSIS model was used to comprehensively evaluate 14 evaluation objects with different irrigation methods and fertilization treatments. The results of the two-year experiment show that the best fertilization treatment under Moistube irrigation and drip irrigation conditions was low-concentration inorganic fertilizer combined with medium-concentration soluble organic fertilizer, which was combined with the best fertilization treatment, and the most suitable irrigation method for greenhouse tomato cultivation in the Loess Plateau was Moistube irrigation. The results of this study also provide practical experience and theoretical support for adaptive irrigation and the integrated management of water and fertilizer.