Submitted to: Advances in Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2014
Publication Date: 1/15/2016
Citation: Delgado, J.A. 2016. 4 Rs are not enough: We need 7 Rs for nutrient management and conservation to increase nutrient use efficiency and reduce off-site transport of nutrients. In: Lal, R., Stewart, B.A., editors. Soil Specific Farming: Precision Agriculture. Advances in Soil Science series. Boca Raton, FL: CRC Press. p. 89-126.
Interpretive Summary: It is important to consider how precision farming jointly with precision conservation can help us address today’s challenges, and how they will contribute to climate change mitigation and adaptation (Delgado et al 2011; Lal et al. 2011). Among today’s important challenges are a changing climate, feeding a continuously growing world population, the depletion of water resources to use for irrigation, desertification, deforestation, and the need to maintain sustainable soils to maintain and/or increase agricultural production. Conservation practices and management will be key to managing these challenges and for food security (Delgado et al., 2011; Lal et al., 2011). Among the new technologies that can help us increase food production, efficiency, and conservation is the use of geospatial technologies for precision agriculture and precision conservation. Managing spatial and temporal variability with precision farming, precision conservation, and precision harvesting could contribute to increased resource use efficiency, sustainability, and reduced environmental impacts. Roberts (2007) reported that we can use these geotechnologies to improve nutrient management to apply the right product, at the right rate, at the right time and at the right place (i.e., the 4 Rs). Berry et al. (2003 and 2005) reported that we can use spatial technologies to increase conservation effectiveness and apply precise conservation practices at the right place. Cox (2005) simplified the Berry et al. (2003) precision conservation concept as applying the right conservation practice, at the right place, at the right time, and at the right scale. We could join these concepts from Roberts and Cox to establish that we need 7 Rs for nutrient management and conservation. If we are to increase conservation effectiveness and nutrient use efficiency and minimize the losses of sediment and nutrients to the environment, we need to apply the right product (fertilizer), at the right fertilizer rate, with the right method of fertilizer application, with the right conservation practice, and with conservation practice at the right place, and at the right scale of conservation practice, both at the right time (right product, right rate, right method, right practice, right place, right scale, and right time; 7 Rs of nutrient management and conservation). Only by applying precision farming together with precision conservation will we be able to minimize the nutrient losses from fields. It takes hundreds of years to form an inch of soil (SSSA 2013) and we can loss it in a thunderstorm, with erosion reducing its fertility and nutrients moving out of the field. We need to apply the 7 Rs of nutrient management and conservation for maximizing conservation and minimizing off site transport of nutrients.
Technical Abstract: Cox (2010) reported that under business as usual, the environmental impacts of nutrient losses from agriculture will not be resolved and that precision conservation and precision regulation are two mechanisms to reduce the environmental impacts of nutrient losses. This is in agreement with the recently released USGAO report (2013) that states that after more than 40 years after the establishment of the Clean Water Act, as of August 2013, the EPA’s assessment of national water quality found that fifty percent of the assessed waters in the USA did not meet the established standards for fishing, swimming, or drinking, with 67% of assessed lakes and 53% of the assessed miles of rivers in the USA impaired, and more of the assessed water bodies not meeting water quality standards than ever before. King et al. (2009) and Cox and Hug (2012) reported that precision regulation does not necessarily need to be forced, and that it could be voluntary by running model analyses, identifying hot spot areas, and assigning conservation programs that are focused on these hot spots areas. A recent USGAO report (2014) reported that after four decades of incentives for conservation of water quality, there are still persistent water quality problems. The Berry et al. (2003; 2005) concept that precision conservation can help reduce nutrient transport to protect water quality is an important alternative that could be considered. This paper tries to bring to the light the importance of precision conservation for increasing nutrient use efficiency, reducing off-site transport of nutrients from fields, and reducing the transport of nutrients across watersheds. This paper suggests that the 4 Rs of precision farming for nutrient management (the right product, at the right rate, at the right time, and at the right place), may not be enough. We need 7 Rs for nutrient management and conservation to increase conservation effectiveness and nutrient use efficiency and minimize the losses of sediment and nutrients from the field. This paper suggests that by applying the right product (fertilizer), at the right fertilizer rate, with the right method of fertilizer application, with the right conservation practice, and with conservation practice at the right place, and at the right scale of conservation practice, both at the right time, (apply the 7 Rs of nutrient management and conservation: right product, right rate, right method, right practice, right place, right scale, and right time), we will minimize nutrient losses from the field and across the watershed.