How to control weeds in pollution-free sweet potato cultivation?

Commonly used herbicides for sweet potato are as follows: 

(1) Caochangmie (Leikela) 70% wettable powder, 3000-3750 grams per hectare mixed with 450-600 liters of water, applied before planting sweet potato or immediately after planting. Mainly controls Alopecurus aequalis, crabgrass, barnyardgrass, foxtail, ryegrass, goosefoot, smartweed, chickweed, etc., and is safe for subsequent crops. 

(2) Dual 72% emulsifiable concentrate, 1.5-2.25 liters per hectare mixed with 450-600 liters of water, applied after soil preparation before planting or immediately after planting. Under dry conditions, it should be shallowly incorporated into the soil. Mainly controls barnyardgrass, crabgrass, yellow foxtail, goosegrass, bluegrass, lovegrass, Brachiaria, ryegrass, Chloris, mustard, small wild sesame, Cyperus esculentus, water starwort, dodder, etc., and is safe for subsequent crops. 

(3) Dahuili (napropamide, napropamide) 50% wettable powder, 1500-2250 grams per hectare, mixed with 600-750 liters of water, applied before planting sweet potato or immediately after planting; under dry conditions, irrigation may be applied after treatment. Mainly controls wild oat, barnyardgrass, crabgrass, foxtail, Alopecurus aequalis, bluegrass, goosegrass, wild goosefoot, cleavers, chickweed, etc. When the dosage of 50% Dahuili is within 2250 grams per hectare, it is safe for subsequent crops. If this dosage is exceeded, phytotoxicity may occur in the next crop of rice, wheat, barley, sorghum, corn and other gramineous crops. Other herbicides also include trifluralin, Goal, haloxyfop-R-methyl, Henaiss, fluazifop-P-butyl, quizalofop-P-ethyl, oxadiazon, sethoxydim, clethodim, and Wiba.