Weeds are a major contributing factor to crop yield loss. Weed control is regularly practiced during the growing season, with many growers making a conscious effort to minimise weed-seed return to the soil seedbank during the cropping program. However, growers may be unintentionally introducing weed seeds through sowing of contaminated crop seed. Using samples of crop seed obtained from 29 growers across two Western Australian grain-growing regions, 81 samples were hand-cleaned to determine weed-seed contamination levels. Of those samples, 41% were weed-free, and in the remaining 59%, the main contaminant was Lolium rigidum (annual ryegrass), occurring in 49% of contaminated samples. Crop type and cleaning method had significant effects on the level of weed-seed contamination, with barley having higher levels of contamination than other crops, and professional contractors providing lower contamination than other methods of cleaning. However, any seed-cleaning method provided significantly cleaner grain samples than no seed cleaning. This study established that crop-seed contamination was evident on Western Australian farms and that growers may be unintentionally sowing weed seeds with their crops. Seed cleaning combined with judicious paddock selection and weed-seed removal during the growing season can lead to weed-free crop seed.

杂草是造成农作物减产的主要因素。在生长期定期进行除草控制，许多种植者有意识地努力在播种计划期间尽量减少杂草返回土壤种子库的过程。但是，种植者可能通过播种受污染的农作物种子而无意中引入了杂草种子。使用从两个西澳大利亚谷物种植区的29个种植者处获得的农作物种子样品，对81个样品进行了手工清洗以确定杂草种子污染水平。在这些样品中，有41％是无杂草的，在其余59％中，主要污染物是刚性黑麦草（一年生黑麦草），占受污染样品的49％。作物类型和清洁方法对杂草种子污染水平有显着影响，大麦的污染水平高于其他作物，专业承包人的污染水平低于其他清洁方法。但是，任何种子清洁方法都比没有种子清洁方法提供了明显更清洁的谷物样品。这项研究确定，西澳大利亚州农场的农作物种子污染很明显，种植者可能无意中将杂草种子与农作物一起播种。在生长季节将种子清洗与明智的围场选择以及除草种子相结合，可以使农作物种子不含杂草。