Legume recovery in pastures following broadleaf weed control

入侵物种在限制牧草产量的牧场中是一个普遍存在的问题。虽然除草剂对杂草仍然有效，但除草剂也会去除已知能以最低成本增加产量的有益豆类。尽管豆科植物迅速回归是一个重要的目标，但在杂草防治后，豆科植物在牧场重建的能力取决于几个因素。这些因素包括喷洒后除草剂的降解率、土壤中是否存在可行的豆类种子，以及在田间条件下有利于豆类幼苗出苗和生长所需的特定生长条件。我们使用田间试验(短期和长期)和配套温室试验相结合的方法来1)量化两种新除草剂(氨基环丙草胺和氨基吡草胺)的“残留”性质的降解，2)评估它们对两种常见豆科牧草(紫花苜蓿和白三叶)施药后的出苗和存活的影响，3)评估环境(光和湿度)对豆科植物幼苗出苗、生长和存活的影响，4)记录喷药后牧场植物种类组成的长期变化，以及5)描述北部温带牧场的土壤种子库，包括豆类的丰度。信息将被用来帮助种植者有效地重建豆类，并保持生产力和牧场生物多样性。

Invasive species are a widespread problem in pastures limiting forage production. While herbicides remain effective against weeds, herbicides also remove beneficial legumes known to increase production at minimal cost. Although prompt return of legumes is an important goal, the ability of legumes to re-establish in pastures following weed control depends on several factors. They include the rate of herbicide degradation following spraying, the presence of viable legume seeds in the soil, and the specific growing conditions needed to favor legume seedling emergence and growth under field conditions. We use a combination of field experiments (short and long-term) and complementary greenhouse trials to 1) quantify the degradation of two new herbicides (aminocyclopyrachlor and aminopyralid) with 'residual' properties, 2) assess their effect on the emergence and survival of two common legumes (alfalfa and white clover) following application, 3) evaluate the effect of environment (light and moisture) on legume seedling emergence, growth and survival, 4) document long-term changes in plant species composition of pasture following spraying, and 5) describe the soil seed bank in northern temperate pastures, including the abundance of legumes. Information will be used to assist growers to effectively re-establish legume and maintain productivity and pasture biodiversity.