Jean L. Steiner

Impact of conservation tillage and nutrient management on soil water and yield of cotton fertilized with poultry litter or ammonium nitrate in the Georgia Piedmont

Abstract Cotton has become a dominant crop in the southeastern USA, but only about 12% of the 620,000xa0ha of cotton ( Gossipium hirsutum L.) in Georgia, for example, is under conservation tillage. Georgia and bordering states produce about 42% of the poultry in the United States and in Georgia alone, this results in over 1.6 million Mg of poultry litter (PL) annually. The fertilizer value of PL is well-recognized but much of it is applied to pastures and only a small percentage is applied to crop land. Limited information is available on the response of cotton to PL as fertilizer in conservation tillage systems in the Southeast. The performance of cotton under two tillage and two fertilizer treatments was evaluated from 1996 to 1999 to highlight management options for increased adoption of conservation tillage and PL use. Cotton, followed by a rye ( Secale cereale L.) cover crop, was grown under a factorial arrangement of tillage (no-till (NT) vs conventional tillage (CT)) and fertilizer (ammonium nitrate, as conventional fertilizer (CF) vs PL) on a Cecil sandy loam (clayey, kaolinitic thermic Typic Kanhapludult; Chromi-Alumic Acrisol) near Watkinsville, Georgia. Average lint yield from 1996 to 1999 was in the sequence no - till poultry litter ( NTPL )> no - till conventional fertilizer ( NTCF )> conventional tillage poultry litter ( CTPL )> conventional tillage and fertilizer ( CTCF ) . Differences were significant at P ≤0.05 for NTPL vs CTPL, NTPL vs CTCF, and NTCF vs CTCF. Average yield differences were also significant between NT and CT but not PL and CF. PL yielded more than CF only in 1997. NT generally had a more favorable soil water regime than CT. Yield differences among treatments occurred during the first 3 years only. Drought in the fourth year reduced yield across all treatments and negated treatment effects. Lint yield would increase in the southeastern USA and an additional outlet for the PL would be created by adopting NT and fertilizing with PL in cotton production.

Production and supply of high‐quality food protein for human consumption: sustainability, challenges, and innovations

The Food and Agriculture Organization of the United Nations estimates that 843 million people worldwide are hungry and a greater number suffer from nutrient deficiencies. Approximately one billion people have inadequate protein intake. The challenge of preventing hunger and malnutrition will become even greater as the global population grows from the current 7.2 billion people to 9.6 billion by 2050. With increases in income, population, and demand for more nutrient‐dense foods, global meat production is projected to increase by 206 million tons per year during the next 35 years. These changes in population and dietary practices have led to a tremendous rise in the demand for food protein, especially animal‐source protein. Consuming the required amounts of protein is fundamental to human growth and health. Protein needs can be met through intakes of animal and plant‐source foods. Increased consumption of food proteins is associated with increased greenhouse gas emissions and overutilization of water. Consequently, concerns exist regarding impacts of agricultural production, processing and distribution of food protein on the environment, ecosystem, and sustainability. To address these challenging issues, the New York Academy of Sciences organized the conference “Frontiers in Agricultural Sustainability: Studying the Protein Supply Chain to Improve Dietary Quality” to explore sustainable innovations in food science and programming aimed at producing the required quality and quantity of protein through improved supply chains worldwide. This report provides an extensive discussion of these issues and summaries of the presentations from the conference.

A system’s approach to assess the exposure of agricultural production to climate change and variability

Estimating the exposure of agriculture to climate variability and change can help us understand key vulnerabilities and improve adaptive capacity, which is vital to secure and increase world food production to feed its growing population. A number of indices to estimate exposure are available in literature. However, testing or validating them is difficult and reveals a considerable variability, and no systematic methodology has been developed to guide users in selecting indices for particular applications. This need is addressed in this paper by developing a flowchart from a conceptual model that uses a system’s approach. Also, we compare five approaches to estimate exposure indices (EIs) to study the exposure of agriculture to climate variability and change: single stressor-mean climate, single stressor-extreme climate, multiple stressor-mean climate, multiple stressor-extreme climate; and combinations of the above approaches. The developed flowchart requires gathering information on the region of study, including its agriculture, stressor(s), climate factor(s) (CF), period of interest and the method of aggregation. The flowchart was applied to a case study in Kansas to better understand the five approaches to estimate EIs and the implications of the choices made in each step on the estimated the exposure. The flowchart provides options that guide EI estimation by selecting the most appropriate stressor(s), associated CF(s), and aggregation methods when a detailed methodological analysis is possible, or proposes a default method when data or resources do not allow a detailed analysis. Climate adaptation involves integration of a multitude of factors across complex systems. A more standardized approach to assessing exposure can promote information sharing across different locations and systems as this rapidly evolving area of study moves forward.

Knowledge and tools to enhance resilience of beef grazing systems for sustainable animal protein production

Ruminant livestock provides meat and dairy products that sustain health and livelihood for much of the worlds population. Grazing lands that support ruminant livestock provide numerous ecosystem services, including provision of food, water, and genetic resources; climate and water regulation; support of soil formation; nutrient cycling; and cultural services. In the U.S. southern Great Plains, beef production on pastures, rangelands, and hay is a major economic activity. The regions climate is characterized by extremes of heat and cold and extremes of drought and flooding. Grazing lands occupy a large portion of the regions land, significantly affecting carbon, nitrogen, and water budgets. To understand vulnerabilities and enhance resilience of beef production, a multi‐institutional Coordinated Agricultural Project (CAP), the “grazing CAP,” was established. Integrative research and extension spanning biophysical, socioeconomic, and agricultural disciplines address management effects on productivity and environmental footprints of production systems. Knowledge and tools being developed will allow farmers and ranchers to evaluate risks and increase resilience to dynamic conditions. The knowledge and tools developed will also have relevance to grazing lands in semiarid and subhumid regions of the world.

History of the USDA-ARS Experimental Watersheds on the Washita River, Oklahoma

A national experimental watershed network, operated by the Agricultural Research Service of the US Department of Agriculture, was established in 1959 to conduct research on the effects of flood retarding structures, upland soil and water conservation practices, and land management on downstream water quantity and quality. Three large watersheds of this network are on the Washita River in Oklahoma, approximately 50 to 80 kilometers south-west of Oklahoma City. They are the Southern Great Plains Research Watershed (SGPRW; 2,900 km2), the Little Washita River Experimental Watershed (LWREW; 610 km²), and the Fort Cobb Reservoir Experimental Watershed (FCREW; 790 km²).

Vulnerability of Southern Plains agriculture to climate change

Projections of greater interannual and intrannual climate variability, including increasing temperatures, longer and more intense drought periods, and more extreme precipitation events, present growing challenges for agricultural production in the Southern Plains of the USA. We assess agricultural vulnerabilities within this region to support identification and development of adaptation strategies at regional to local scales, where many management decisions are made. Exposure to the synergistic effects of warming, such as fewer and more intense precipitation events and greater overall weather variability, will uniquely affect rain-fed and irrigated cropping, high-value specialty crops, extensive and intensive livestock production, and forestry. Although the sensitivities of various agricultural sectors to climatic stressors can be difficult to identify at regional scales, we summarize that crops irrigated from the Ogallala aquifer possess a high sensitivity; rangeland beef cattle production a low sensitivity; and rain-fed crops, forestry, and specialty crops intermediate sensitivities. Numerous adaptation strategies have been identified, including drought contingency planning, increased soil health, improved forecasts and associated decision support tools, and implementation of policies and financial instruments for risk management. However, the extent to which these strategies are adopted is variable and influenced by both biophysical and socioeconomic considerations. Inadequate local- and regional-scale climate risk and resilience information suggests that climate vulnerability research and climate adaptation approaches need to include bottom-up approaches such as learning networks and peer-to-peer communication.

Regional grassland productivity responses to precipitation during multiyear above- and below-average rainfall periods

There is considerable uncertainty in the magnitude and direction of changes in precipitation associated with climate change, and ecosystem responses are also uncertain. Multiyear periods of above- and below-average rainfall may foretell consequences of changes in rainfall regime. We compiled long-term aboveground net primary productivity (ANPP) and precipitation (PPT) data for eight North American grasslands, and quantified relationships between ANPP and PPT at each site, and in 1-3xa0year periods of above- and below-average rainfall for mesic, semiarid cool, and semiarid warm grassland types. Our objective was to improve understanding of ANPP dynamics associated with changing climatic conditions by contrasting PPT-ANPP relationships in above- and below-average PPT years to those that occurred during sequences of multiple above- and below-average years. We found differences in PPT-ANPP relationships in above- and below-average years compared to long-term site averages, and variation in ANPP not explained by PPT totals that likely are attributed to legacy effects. The correlation between ANPP and current- and prior-year conditions changed from year to year throughout multiyear periods, with some legacy effects declining, and new responses emerging. Thus, ANPP in a given year was influenced by sequences of conditions that varied across grassland types and climates. Most importantly, the influence of prior-year ANPP often increased with the length of multiyear periods, whereas the influence of the amount of current-year PPT declined. Although the mechanisms by which a directional change in the frequency of above- and below-average years imposes a persistent change in grassland ANPP require further investigation, our results emphasize the importance of legacy effects on productivity for sequences of above- vs. below-average years, and illustrate the utility of long-term data to examine these patterns.

Climate change impacts on soil and water conservation

Climate change and particularly precipitation changes will affect water runoff and soil erosion from agricultural cropland, but will the change be large enough to warrant modifications in U.S. conservation policy or practice? In a 2003 report by the Soil and Water Conservation Society (SWCS), this question was answered with an emphatic yes [SWSC, 2003]. Impacts of projected precipitation changes on soil erosion and runoff are complex, display high regional and temporal variability, and depend on a number of nonclimatic factors, such as seasonal timing of agronomic practices and antecedent soil moisture conditions. Altogether, observed and projected changes in precipitation are believed to substantially heighten the risk of runoff, soil erosion, and related environmental consequences. This article reports on a follow-up workshop that called for a review of current approaches to estimating soil erosion and runoff on agricultural lands, enhancements to soil and water planning tools, and strengthening of conservation practices and standards.

Response of conservation tillage sorghum to growing season precipitation

Abstract In earlier crop rotation studies in which grain sorghum ( Sorghum bicolor (L.) Moench) followed winter wheat ( Triticum aestivum L.) after a 10- to 11-month fallow period during which the wheat residues were managed by different tillage methods, sorghum yields increased in response to increases in soil water content at sorghum planting time. Similar results were obtained when residues were placed on the surface at the start of the fallow period. The soil water contents at planting time were positively correlated with amounts of wheat residue maintained on the soil surface during fallow. The studies also suggested that sorghum responded positively to growing season precipitation when increasing of residue remained on the soil during the growing season. The objective of this study was to evaluate this response to growing season precipitation through statistical analyses of data from five earlier tillage and residue placement studies. Regression analyses of data from the studies showed that sorghum grain yields increased with increasing amounts of surface residues at planting time. Differences in response of grain yield to precipitation were greatest in the vegetative period. For the period, grain yields increased 0.014 Mg ha −1 per mm of precipitation when residue amounts ranged from 0 to 0.4 Mg ha −1 per mm of precipitation when residue amounts ranged from 0 to 0.4 Mg ha −1 , and 0.027 Mg ha −1 per mm of precipitation when residue amounts were ⪢ 3.2 Mg ha −1 . Differences in response to rainfall in the heading and grain filling period were lower or negligible. High responses for the vegetative period were attributed to the residues which increased infiltration and reduced evaporation before canopy development. Lower responses during heading and lack of responses during grain filling were attributed to: (1) canopy development, which minimized the effect of residues on imfiltration and evaporation; (2) soil cracking, which resulted in similar infiltration with all treatments; and (3) residue decomposition, which minimized differences among residue amounts on the soil with different treatments.

Water Budget Considerations Regarding Groundwater Extraction Targets in the Calera Aquifer Watershed, Mexico

Groundwater extraction from the Calera Aquifer in the State of Zacatecas, Mexico, for irrigation, urban, and industrial uses has increased over recent decades to unsustainable levels. An annual, watershed-scale water budget analysis was conducted to identify alternative water conservation and water use scenarios, and to determine their effectiveness at reducing groundwater extraction. The scenario analysis showed that even with a 10% reduction in industrial and urban water use and a 50% reduction in irrigation water the annual groundwater deficit remains above 10 [10 6 m 3 /yr]. The political and socioeconomic impacts of such large reductions in water use are likely to be unacceptable. At best, a freezing of industrial and urban water use at the level of year 2010 and a 50% reduction in irrigation water use can be hoped for, which leads to an annual groundwater deficit of about 20 [10 6 m 3 /yr]. This is a great improvement over the 75 [10 6 m 3 /yr] groundwater deficit of year 2010, and could potentially be adopted as a target deficit that qualifies as sustainable utilization of groundwater resources. To achieve a 50% reduction in irrigation water use will likely involve a combination of higher irrigation efficiencies,