Agroeconomic Analysis of Nitrate Crop Source Reductions

Medellín–Azuara, Josué; Rosenstock, Todd S.; Howitt, Richard E.; Harter, Thomas; Jessoe, Katrina; Dzurella, K.; Pettygrove, Stuart; Lund, Jay R.

doi:10.1061/(asce)wr.1943-5452.0000268

Cited by 7 publications

(6 citation statements)

References 20 publications

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“…The mass balance parameters that have the most leverage on the N systems are associated with the cropping system: synthetic fertilizer, manure applications, and N in harvested crops (Miller and Smith, 1976; Zhang et al, 1998). We describe the mass balance methods for these N flows in detail along with a brief description of methods used to compute others including development of historical land use maps that underlie the calculations.…”

Section: Methodsmentioning

confidence: 99%

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Agriculture's Contribution to Nitrate Contamination of Californian Groundwater (1945-2005)

et al. 2014

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895Nitrogen (N) use in intensive agriculture can degrade groundwater resources. However, considerable time lags between groundwater recharge and extraction complicate source attribution and remedial responses. We construct a historic N mass balance of two agricultural regions of California to understand trends and drivers of past and present N loading to groundwater . Changes in groundwater N loading result from historic changes in three factors: the extent of agriculture (cropland area and livestock herd increased 120 and 800%, respectively), the intensity of agriculture (synthetic and manure waste effluent N input rates increased by 525 and 1500%, respectively), and the efficiency of agriculture (crop and milk production per unit of N input increased by 25 and 19%, respectively). The net consequence has been a greater-than-order-of-magnitude increase in nitrate (NO 3 -) loading over the time period, with 163 Gg N yr -1 now being leached to groundwater from approximately 1.3 million ha of farmland (not including alfalfa [Medicago sativa L.]). Meeting safe drinking water standards would require NO 3 -leaching reductions of over 70% from current levels through reductions in excess manure applications, which accounts for nearly half of all groundwater N loading, and through synthetic N management improvements. This represents a broad challenge given current economic and technical conditions of California farming if farm productivity is to be maintained. The findings illustrate the growing tension-characteristic of agricultural regions globally-between intensifying food, feed, fiber, and biofuel production and preserving clean water.

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Section: Methodsmentioning

confidence: 99%

“…While theoretically plausible and even practically sustainable, it would mean that many production systems operate near N equilibrium. Achieving this level of efficiency would require transformative changes in how these systems were managed, which is often at great cost to the farmer (Medellín-Azuara et al, 2013).…”

Section: Constraints On Remediesmentioning

confidence: 99%

Agriculture's Contribution to Nitrate Contamination of Californian Groundwater (1945-2005)

et al. 2014

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“…A variety of potential solutions to address the nitrate leaching problem and improve groundwater quality have been proposed, including regulations to reduce nitrogen (N) fertilizer use (i.e., fertilizer tax, cap, and trade programs) (Medellin-Azuara et al, 2013) and best management practices (i.e., using appropriate crop fertilizer templates, efficient irrigation management, cover cropping) (Di and Cameron, 2002;Hartz, 2006;Shepherd and Chambers, 2007). But solving this complex nitrate problem is expected to take decades and require significant changes in agricultural practices.…”

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confidence: 99%

Can We Grow Organic or Conventional Vegetables Sustainably Without Cover Crops?

Brennan¹

2017

hortte

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Vegetable and fruit consumption patterns in the United States indicate that most people need to eat far more fruits and vegetables to meet the current nutritional guidelines for a healthy diet. Following these guidelines would require more than doubling the harvested acreage for fruits and vegetables and could have serious environmental implications if unsustainable production practices were used. This situation will likely intensify with population growth and climate change. To answer the title question (can we grow organic or conventional vegetables sustainably without cover crops?), this paper focuses on the high-input, tillage-intensive vegetable production practices in the Salinas Valley of California, a region often called “the Salad Bowl of America.” This region has a serious problem of nitrate contamination of the groundwater that occurred as the agricultural systems here shifted from agronomic to high-value horticultural crops [primarily vegetables and strawberries (Fragaria ×ananassa)] over the past several decades. This raises questions about the sustainability of past and current vegetable production practices and indicates the need for a radical paradigm shift in nutrient management. Cover cropping is well recognized as a “best management practice” in vegetable production systems, but is still relatively uncommon in many of the most important vegetable production regions in the United States, including the Salinas Valley. It is argued that cover crops are an essential part of sustainable vegetable production because they provide a complex suite of unique ecosystem services during fallow periods that complement best management practices during cash crop periods. The reasons that cover crops are uncommon here are discussed and three alternative cover cropping strategies are described to potentially increase adoption of cover cropping in vegetable rotations. These strategies are focused on reducing residue management challenges and include a novel strategy to extract the juice from nitrogen-rich, immature cover crops for use as a liquid organic fertilizer in subsequent cash crops.

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“…Current over-reliance on groundwater reserves for crop applied water has stressed California's aquifers [56]. Furthermore, other forms of agriculture have generated excess nitrogen throughout the region [57,58], which can lead to myriad impacts on environmental [59] and agroeconomic systems [60], and ultimately human well-being. Remedies in this region include enhancing viticulture in active recharge zones around groundwater dependent communities [61], constructing distributed desalination systems for brackish irrigation return water [62], incorporating wildlife friendly farming practices [63], and integrated management of forests and watersheds for clean water supply [64].…”

Section: Land Use Considerationsmentioning

confidence: 99%

sUAS Remote Sensing of Vineyard Evapotranspiration Quantifies Spatiotemporal Uncertainty in Satellite-Borne ET Estimates

Kalua¹,

Rallings

Booth

et al. 2020

Remote Sensing

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Small Unmanned Aerial Systems (sUAS) show promise in being able to collect high resolution spatiotemporal data over small extents. Use of such remote sensing platforms also show promise for quantifying uncertainty in more ubiquitous Earth Observation System (EOS) data, such as evapotranspiration and consumptive use of water in agricultural systems. This study compares measurements of evapotranspiration (ET) from a commercial vineyard in California using data collected from sUAS and EOS sources for 10 events over a growing season using multiple ET estimation methods. Results indicate that sUAS ET estimates that include non-canopy pixels are generally lower on average than EOS methods by >0.5 mm day−1. sUAS ET estimates that mask out non-canopy pixels are generally higher than EOS methods by <0.5 mm day−1. Masked sUAS ET estimates are less variable than unmasked sUAS and EOS ET estimates. This study indicates that limited deployment of sUAS can provide important estimates of uncertainty in EOS ET estimations for larger areas and to also improve irrigation management at a local scale.

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Agroeconomic Analysis of Nitrate Crop Source Reductions

Cited by 7 publications

References 20 publications

Agriculture's Contribution to Nitrate Contamination of Californian Groundwater (1945-2005)

Agriculture's Contribution to Nitrate Contamination of Californian Groundwater (1945-2005)

Can We Grow Organic or Conventional Vegetables Sustainably Without Cover Crops?

sUAS Remote Sensing of Vineyard Evapotranspiration Quantifies Spatiotemporal Uncertainty in Satellite-Borne ET Estimates

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