Guan'gai paishui xuebao (Oct 2021)
The Effects of Seasonal Drought on Rainfall Infiltration in Pineapple Plantation under Mulched Drip Irrigation
Abstract
【Background and objective】 Mulched drip irrigation is often used in dry regions for water-saving, but the mulching film could hinder rainfall infiltration and enhance surface runoff as a result. This could reduce the use of natural rainfall by plants, especially in regions where rainfall is abundant in summer and autumn while scarce in other seasons. The objective of this paper is to evaluate the balance of mulched drip irrigation in saving water in dry seasons and losing water in other seasons due to the increased surface runoff. 【Method】 We took pineapple orchard as an example and conducted the experiment in a field comprising three irrigation treatments: conventional rain-fed cultivation (CK), conventional drip irrigation (DF), and mulched drip irrigation with plastic film (MF). In each treatment, we measured the change in moisture in the 0~100 cm soil profile using FDR sensors. 【Result】 Both conventional and mulched drip irrigation reduced rainfall infiltration in the planting rows. The total rainfall infiltration in the 0~100 cm soil profile on the planting ridge under DF and MF was 48.4% and 60.8% respectively lower than that under conventional rain-fed cultivation, despite that MF did not affect the water use efficiency and fruit yield. Compared with CK, DF and MF increased agronomic productivity of the water by 37.5% and 13.8% respectively, and field biomass by 13.8% and 52.2% respectively. MF also increased rainfall infiltration in the 40~100 cm soil in the burrow between the planted ridges. The rainfall infiltration ratio of moderate rainfall, heavy rainfall and rainstorm was 3.5%, 15.8% and 30.3% for DF, 2.5%, 16.7% and 31.5% for DF, and 15.7%, 39.7% and 43.0% for MF. The wetting depth (accounted for when soil moisture increase was >4%) associated with moderate rainfall, heavy rainfall and rainstorm was 30 cm, 100 cm and 30 cm for CF, 20 cm, 30 cm and 20 cm for DF, and 10 cm, 50 cm and 20 cm for MF. It was found that the mulched drip irrigation stabilized soil moisture in the planting rows; in rainy season, the depth of soil moisture content affected by CK, DF and MF was 0~30 cm, 0~20 cm and 0~10 cm respectively. 【Conclusion】 In regions rich in rainfalls in summer and autumn while dry in other seasons, mulched drip irrigation reduced rainfall infiltration and promoted deep infiltration of rainfall, but it does not affect water agronomic productivity and biomass of the pineapple. It is hence beneficial to saving water and increasing pineapple yield.
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