Optimization of technical parameters for rice straw fiber-based mulch

Abstract: The long term use of farmland plastic mulching not only brings us economic benefit, but also brings the hidden danger of pollution. Residual film existing in the soil will affect the growth and development of crop root and the transfer of water-fertilizer, and meanwhile will lead to the crop yield reduction. By using rice straw as the main raw material, the straw fiber mulch can achieve green (organic) cultivation and scientific straw returning to the field, and reduce agricultural non-point source pollution effectively. However, the characteristics of increasing temperature in soil need to be further improved, since the fiber mulch is milky and transmittance is low, into which the infrared in the daytime sunlight less streamed, leading to plants and soil heat reduction. When there exists the difference between atmosphere and intramembranous temperature, the heat will dissipate if the temperature is high in the straw fiber film, which leads to the thermal insulation performance not ideal. In order to improve the deficiency of temperature increasing of straw fiber mulch, and make it have a better practicability to replace the plastic mulching in an all-round way, the technology parameters of staining the milky straw fiber mulch to green were studied, and the solar hot light transmittance was increased and the soil temperature loss was further reduced by adding environmental protection functional additive to decrease the air permeability of the fiber mulch. The five-factor and five-level quadratic regression orthogonal rotation center combined method was applied. Functional additive is added at a constant temperature of 60℃ for 45 min in the wet process of dyeing, and mixed thoroughly until it is completely combined, and the pH value of fiber pulp is controlled to be stable at 6.0. Using the wood pulp fibers to build skeleton, and adding rice straw fiber as the main filling material, supplemented by safe and environmental protection synthetic food dyes, such as lemon yellow and brilliant blue dye, the straw fiber pulp, dye addition, brilliant blue proportion, modifier addition and the mass fraction of wet strength agent as influence factors were studied, as well as the air permeability, dye uptake, fading rate, dry tensile strength and wet tensile strength as the performance evaluation indices. The optimal technology parameters of green straw fiber mulch were determined as follows: rice straw fiber pulp addition amount of 71%~79%, dye addition of 0.44%~0.53%, proportion of the brilliant blue of 90%, modifier addition of 0.6%, and the wet strength agent addition of 0.9%. Under such an optimized combination, we come up with a result in the evaluation of the indicators: The air permeability is lower than 2 μm/Pa·s, the dye uptake is higher than 80%, the fading rate is lower than 8%, the dry tensile strength is more than 40 N and the wet tensile strength is more than 16 N, which can meet the technical requirements of the cultivation of organic (green) crops field through covering the rice straw field mulch, and the hot light transmittance will increase and the air permeability will decrease, which will further improve the performance of heat preservation and moisture conservation.