USDA LTAR Common Experiment measurement: Aboveground biomass v1

The most important ecosystem service from agriculture is the provision of food, fiber, feed, and fuel. These outputs from the system are almost always a function of the amount of biomass accumulated above the soil surface (except with root crops). Measuring the aboveground biomass is necessary for determining the amount of plant material allocated to vegetative and reproductive organs. The amount of biomass allocated to these organs will vary to some degree each year due to interactions among the genetics, environment, and stressors. Measuring the vegetative-to-reproductive biomass ratio across treatments, landscapes, and years is an important metric and this ratio is termed the “harvest index.” The harvest index provides insight into improving management and cost efficiency in response to positive and negative impacts incurred from local (e.g., soil quality, pest and disease pressure, and weather), technological (e.g., genomic enhancement, precision inputs, and remote sensing/AI), or systematic (e.g., market, policy, and climate) sources. The amount of biomass remaining in the field is additionally important for determining the amount of C, N, P, K, S, and other nutrients returned to the soil. These data, paired with nutrient export and off-site losses, enable the construction of nutrient balances critical in evaluating tradeoffs among ecosystem services provided by agricultural landscapes. This protocol describes the methods used to collect aboveground biomass which includes everything that: Stays in the field: such as stem, stalk, branches, leaves, grain enclosures (such as pod shells and husk leaves), and grain support structures (such as cob and ear shank), and Leaves the field: such as grain, hay, fiber, and plant material for bioenergy production.