Method for tapping yield potential of saccharum officinarum by controlling time of plastic mulching

A method for tapping a yield potential of sugarcane by controlling an uncovering time of a plastic mulching, comprising the following steps:

• (1) planting sugarcane seedlings in a sugarcane furrow in a sugarcane field, covering with soil and watering the sugarcane seedlings;
• (2) applying the plastic mulching, wherein the plastic mulching comprises covering the sugarcane furrow fully with a plastic film directly above the sugarcane furrow in a direction parallel to the sugarcane furrow, and covering the plastic film with a soil with a predetermined thickness along the sugarcane furrow, such that the plastic film is tightly attached to the soil in the sugarcane furrow, wherein the plastic film is a fully biodegradable film, a weeding polyethylene film, or an ordinary polyethylene film;
• (3) determining an optimal uncovering time for the plastic mulching by:
• performing, based on two-year data comprising a complete degradation condition of the plastic film mulching a soil surface and a yield change pattern of the sugarcane, a logistic fitting on a yield impact according to a regression equation
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• and deriving a curve equation
• y
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• accurately determining the time of plastic mulching at three time points, namely
• t
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• deriving, through a 100-times descent iterative fitting, the three time points as endpoints, namely day 0, day 58, and day 119, wherein t1 is −3 through a formula calculation, but considering that the time of plastic mulching is a non-negative number, t1 is limited to 0;
• in the 100-times descent iterative fitting, through an observation, there is no significant yield change after a time point defined by day 156;
• and therefore, the time of plastic mulching is divided into four mulching periods, namely a mulching period with a medium-to-low yield potential, defined by days 0-58, with a yield potential of 32.8-77.5 t/ha, a mulching period with a medium-to-high yield potential, defined by days 58-119, with a yield potential of 77.5-122.2 t/ha, a mulching period with a high yield potential, defined by days 119-156, with a yield potential of 122.2-138.8 t/ha, and an ineffective mulching period after day 156, with no significant yield increase;
• (4) uncovering the plastic film at the optimal uncovering time by allowing the plastic film to biodegrade;
• or uncovering the plastic film at the optimal uncovering time by removing the soil on the plastic film, cleaning the plastic film out of the sugarcane field by a plastic film recycling machine or a manual recycling method, and sending a recycled plastic film to a plastic film recycling station for a centralized treatment;
• and
• (5) harvesting the sugarcane after the sugarcane has matured, wherein the sugarcane has a yield of 122.2-138.8 t/ha.