4R Implementation for Sustainable Cropping Systems
Production demands, input requirements and environmental impacts taken together mean the risks for making the wrong nutrient use decisions is greater now than ever. When fertilizer BMPs result in increased production and input use efficiency, they also reduce losses to the environment. When making practice selection, the interconnectivity between practices addressing source, rate, time and place should be considered.While the scientific practices governing the 4Rs are universal, practice implementation is site-specific; so there is not a common management plan or set of practices that will work for everyone in every location. Crop advisors are key in the efforts to increase adoption of 4R Nutrient Stewardship with growers.
Selecting BMPs for increasing nutrient efficiency and productivity while reducing environmental impact begins with addressing the scientific principles behind the 4Rs. Fertilizer BMPs should be selected based on these principles, and should then be used in combination with other conservation practices.
Right Source:
Ensure a balanced supply of essential nutrients, considering both naturally available sources and the characteristics of specific products in plant-available forms. Specifically, consider nutrient supply in plant-available forms, ensure the nutrient suits soil properties, and recognize the synergisms among elements.Right Rate:
Assess and make decisions based on soil nutrient supply and plant demand. Specifically, appropriately assess soil nutrient supply (including from organic sources and existing soil levels), assess plant demand, and predict fertilizer use efficiency.
Right Time:
Assess and make decisions based on the dynamics of crop uptake, soil supply, nutrient loss risks and field operation logistics. Specifically, assess the timing of crop uptake, assess the dynamics of the soil's nutrient supply, recognize weather factors, and consider logistics.Right Place:
Address root-soil dynamics and nutrient movement, and manage spatial variability within the field to meet site-specific crop needs and limit potential losses from the field. Specifically, recognize root/soil dynamics, manage spatial variability issues, consider the tillage system, and limit potential off-field transport.