Studies with 33 soils selected to obtain a wide range in properties showed that the surface area values obtained by an ethylene glycol monoethyl ether (EGME) procedure that omitted the customary pretreatments to remove organic matter and saturate the soil sample with Ca2+ were similar to, and very highly significantly correlated with, the values obtained when these time‐consuming pretreatments were included. The surface area values obtained by the simplified EGME procedure were very highly significantly correlated with the clay contents and cation‐exchange capacities of the soils studied.

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The Conservation Reserve Program (CRP) is a U.S. federal land conservation program that incentivizes grassland reestablishment on marginal lands. Although this program has many environmental benefits, two critical questions remain: does reestablishing grasslands via CRP also result in soil health recovery, and what parts of restored fields (i.e., topographic positions) recover the fastest? We hypothesized that soil health will recover over time after converting cropland to CRP grassland and that recovery will be greatest at higher topographic positions. To test this, we sampled 241 midwestern U.S. soils along a grassland chronosequence (0-40 yr, including native grasslands) and at four topographic positions (i.e., a chronotoposequence). Soils were measured for bulk density, maximum water holding capacity (MWHC), soil organic C (SOC), extractable inorganic N, potentially mineralizable C (PMC), and N. Native grasslands had superior soil health compared with cropland and most CRP soils, and even 40 yr since grassland reestablishment was not adequate for full soil health recovery. Topographic position strongly influenced soil health indicators and often masked any CRP effect, especially with MWHC and SOC. However, PMC (a measure of active C) responded most rapidly to CRP and consistently across the landscape and was 26-34% greater 19-40 yr after grassland reestablishment. Reestablishing grasslands through CRP can improve soil health, although topographic position regulates the recovery, with greatest improvements at shoulder slope positions. Patience is needed to observe changes in soil health, even in response to a drastic management change like conversion of cropland to CRP grassland.

The destruction of the South Vietnamese rice (Oryza sativa L) crop using an arsenic-based herbicide known as Agent Blue during the American Vietnam War (1965-1972) was not a secret; however, it received little media attention in the United States. Republic of Vietnam and United States (U.S.) militaries began destroying food crops (rice) in November of 1962 primarily via aerial applications in the Mekong Delta and Central Highlands of South Vietnam. Spraying of Agent Blue on 100,000 ha of mangrove forests and about 300,000 ha of rice paddies just before rice harvest time resulted in the destruction of the standing crop and rendered the land contaminated with arsenic (As). Six Rainbow herbicides, commonly called Agent Orange, Agent Green, Agent Pink, Agent Purple, Agent White, and Agent Blue, were sprayed on wetlands, rice paddies, forests, mangroves, bamboo and military base perimeter fences to defoliate jungle vegetation, reveal guerilla hiding places and destroy the food supply of enemy troops. South Vietnamese farmers, U.S. and Republic of Vietnam military personnel, and communist insurgents were exposed to these herbicides with immediate and longer term impacts on personal health, civilian household food security and population-wide famine. Agent Blue (cacodylic acid, C 2 H 2 AsO 2 ,) was the most effective of all the Rainbow herbicides in killing rice and grasses. Manufacturing of cacodylic acid began in the late 1950s in the U.S. at the Ansul Company chemical plant in Marinette, Wisconsin and Menominee, Michigan. During the Vietnam War, ocean going ships were loaded with 208-liter Agent Blue barrels and shipped via the St. Lawrence Seaway to the coast of South Vietnam. Arsenic (As) is a naturally occurring element that is found throughout SE Asia deltas including the Mekong Delta. Today arsenic contaminated rice and groundwater are grow

Crambe seed (Crambe abyssinica) is an excellent, recently established source of high-erucic acid oil. Erucic acid has a number of important and potential applications. To develop this potential, a rapid bench-scale method was desired whereby purified erucic acid in up to several 100-g quantities could be produced from crambe seed. Using the method developed, oil was expressed from dried, intact seed; clarified, degummed, and bleached; and saponified and acidified to obtain the free fatty acids. Analysis by inductively coupled plasma of the free fatty acids showed negligible levels of phosphorus and most minerals. Erucic acid was twice crystallized from 95% ethanol at −14°C, resulting in a purity of 87.1%. This process yielded 365 g erucic acid crystals per kg bleached oil. Nuclear magnetic resonance analysis showed that the prepared erucic acid had an excellent pattern of correlation with a commercial standard. The time needed to convert 1 kg of crambe seed to erucic acid is about 48 h. Crystal filtration and drying stages under the current process conditions require 30% of the overall time. The method is suitable for producing adequate quantities of erucic acid for use in studies of its bench-scale conversion. There is obviously, still, a fruitful field of work to be explored in the formalization of refining procedures for crambe oil. It seems that crambe is destined to continue expansion into the higherucic acid oil markets.Paper no. J9058 in JAOCS 76, 801-809 (July 1999).

A practical variable‐rate fertilizer application should be based on information gathered at low cost that represents field fertility levels. The number of soil samples gathered and analyzed may limit the effectiveness of some variable‐rate fertilizer applications. Topography‐based soil sampling is attractive because it suggests a lower number of samples needed to characterize fertility levels and patterns in a field than some current grid sampling recommendations. A 40‐acre North Dakota field consisting of Barnes loam (fine loamy, mixed, Udic Haploborolls), Swenoda loam (mixed, Pachic Udic Haploborolls), and Wyard clay loam (fine loamy, mixed, frigid Typic Haplaquolls) soil types was sampled in a 110 ft grid each fall from 1994 to 1996. Nitrate N, P, sulfate S, and chloride level patterns were similar in all 3 yr. Correlation of both area‐ (sample cores obtained from a wide area within a topography zone) and point‐based (a topography zone represented by a composite taken from a point location) topography sampling with the 110 ft grid values was compared with correlation from a 220 ft, 330 ft, and 5 acre grid. Area‐based topography sampling for nitrate N was superior in correlation to the 220 ft grid values in 2 of 3 yr. Area‐based topography sampling with P was superior to the 220 ft grid in only 1 of 3 yr, but was superior to the 5 acre grid in all years. The 220 ft grid was superior to topography sampling for sulfate S in all years, but area‐based topography sampling was better than the 330 ft grid in 2 of 3 yr and superior to the 5 acre grid in all years. Area‐based topography sampling for chloride was superior to the 220 ft grid in 1 of 3 yr, but was more highly correlated with the 110 ft grid than the 330 ft and 5 acre grid in all years. Area‐based topography sampling was more highly correlated than point‐based topography sampling in seven of 12 comparisons. Topography‐based sampling for nitrate N better represented fertility patterns than did grid sampling. Research Question In order for variable‐rate fertilizer application to be practical, soil testing information must be gathered at low cost, but at the same time represent the variation in field soil fertility levels. Since collecting and analyzing soil samples is expensive, minimizing the number of samples collected while maintaining a high level of soil fertility information is important. This study of one North Dakota field compared the use of topography‐based sampling with selected grid methods for nitrate N, P, sulfate S, and chloride to determine whether topography‐based sampling might compare favorably with information gathered from grid sampling methods, while decreasing the number of samples needed to provide similar or superior soil fertility information. Literature Summary Previous work in Wisconsin and Illinois has suggested that a one sample per acre grid might be required to gather soil fertility information needed for a variable‐rate fertilizer application. Other studies have demonstrated that some soil fertility factors may be related to l...

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