Macronutrient in soils and wheat from long-term agroexperiments reflects variations in residue and fertilizer inputs.

Previous studies in the long-term experiments at Pendleton, OR (USA), were focused on organic matter cycling, but the consequences of land management for nutrient status over time have received little attention. Soil and wheat (Triticum aestivum L.) tissue samples were analyzed to determine the macronutrient dynamics associated with residue management methods and fertilizer rate under a dryland winter wheat-fallow rotation. The treatments included: no burn residue incorporation with farmyard manure (FYM) or pea vines, no burn or spring burn with application of N fertilizer (0, 45, and 90 kg ha-1), and fall burn wheat residue incorporation. The results revealed no differences on the effect of residue burning on macronutrient concentration over time. After receiving the same treatments for 84 years, the concentrations of soil organic C, total N and S, and extractable Mg, K, P in the 0-10 cm depth significantly increased in FYM plots compared to the rest of the plots. The N fertilization rate of 90 kg ha-1 reduced the accumulations of P, K, and Ca in grain compared to the 0 and 45 kg N ha-1 applications. The results indicate that residue incorporation with FYM can play vital role in reducing the macronutrient decline over time.

Micronutrients decline under long-term tillage and nitrogen fertilization.

Tillage and nitrogen (N) fertilization can be expected to alter micronutrient dynamics in the soil and in plants over time. However, quantitative information regarding the effects of tillage and N application rates on micronutrient dynamics is limited. The objectives of this study were (a) to determine the long-term effect of different tillage methods as well as variation in N application rates on the distribution of Mehlich III extractable manganese, copper, zinc, boron, and iron in soils and (b) to assess accumulation of the same nutrients in wheat (Triticum aestivum L.) tissues. The system studied was under a dryland winter wheat-fallow (WW-F) rotation. Tillage methods included moldboard (MP), disk (DP) and sweep (SW), and the N application rates were 0, 45, 90, 135, and 180 kg ha-1. The concentration of soil manganese was greater under DP (131 mg kg-1) than under MP (111 mg kg-1). Inorganic N application reduced extractable soil copper while, it increased manganese accumulation in wheat grain over time. Comparison of micronutrients with adjacent long-term (since 1931) undisturbed grass pasture revealed that the WW-F plots had lost at least 43% and 53% of extractable zinc and copper, respectively, after 75 years of N fertilization and tillage. The results indicate that DP and inorganic N application could reduce the rate of micronutrient decline in soil and winter wheat grain over time compared to MP and no N fertilization.

Hydrodistillation Extraction Kinetics Regression Models for Essential Oil Yield and Composition in Juniperus virginiana, J. excelsa, and J. sabina.

The chemical profile and antioxidant capacity of Juniperus virginiana, J. excelsa, and J. sabina essential oil (EO) fractions as a function of time was the subject of this study. The hypothesis was that, capturing EO in sequential timeframes during hydrodistillation would generate fractions containing unique compositions and antioxidant capacity. In J. virginiana, the highest limonene (43%) was found in the 0⁻5 min oil fraction, with safrole (37%) being highest in the 10⁻20 and 20⁻40 min fractions, and elemol (34%) being highest in the 160⁻240 min fraction. In J. excelsa, α-pinene (34-36%) was the highest in the 0⁻5 min fraction and in the control (non-stop 0⁻240 min distillation) oil, limonene (39%) was the highest in the 0⁻10 min fractions and cedrol (50-53%) was the highest in the 40⁻240 min fractions. In J. sabina, sabinene (80%) was highest in the 0⁻3 min fraction. The highest antioxidant capacity of J. virginiana was demonstrated by the 5⁻10 min fraction; the one in J. sabina by the 3⁻10 min fraction; and, the one in J. excelsa, by the control. The kinetics regression models that were developed can predict EO composition of the three juniper species eluted at different timeframes. Various industries could benefit from the results from this study.

Yield, Composition and Antioxidant Capacity of the Essential Oil of Sweet Basil and Holy Basil as Influenced by Distillation Methods.

The profile and bioactivity of essential oil (EO) depends on genetic, environmental, and other factors. We hypothesized that the basil EO may be influenced by the distillation methods. Hence, a study was conducted to evaluate the effect of steam distillation (SD) and hydrodistillation (HD) extraction method on the yield, composition, and bioactivity of EO of sweet basil (Ocimum basilicum) and holy basil (Ocimum tenuiflorum). In both basil species, the EO yield (content) was significantly higher from SD than from HD. There were significant differences in the compounds' concentrations of EO obtained from SD and HD as well, however, the same compounds were identified in the EO from HD and SD. In the EO of O. basilicum, the concentration of 74% of the identified compounds were higher in SD than HD, whereas in the EO of O. tenuiflorum, the concentration of 84% of identified compounds were higher in SD than in HD. However, the concentrations of two of the major compounds of O. basilicum EO (estragole and methyl cinnamate) and a major compound of O. tenuiflorum EO (methyl eugenol) were significantly higher in HD than in SD. The type of distillation did not affect the antioxidant capacity of basil EO within the species. This study demonstrated that the type of distillation may significantly affect oil yield and composition but not the antioxidant capacity of the EO from sweet and holy basil.

Method for Attaining Caraway Seed Oil Fractions with Different Composition.

Caraway (Carum carvi L.) is a medicinal and aromatic plant; its seeds (fruits) are used as spice and they contain essential oils. We hypothesized that by collecting caraway oil at different time points during the extraction process, we could obtain oil fractions with distinct chemical composition. A hydrodistillation time (HDT) study was conducted to test the hypothesis. The caraway seed oil fractions were collected at eight different HDT (at 0 - 2, 2 - 7, 7 - 15, 15 - 30, 30 - 45, 45 - 75, 75 - 105, and 105 - 135 min). Additionally, a non-stop HD for 135 min was conducted as a control. Most of the oil was eluted early in the HD process. The non-stop HDT treatment yielded 2.76% oil by weight. Of the 24 essential oil constituents, limonene (77 - 19% of the total oil) and carvone (20 - 79%) were the major ones. Other constituents included myrcene (0.72 - 0.16%), trans-carveol (0.07 - 0.39%), and ß-caryophyllene (0.07 - 0.24%). Caraway seed oil with higher concentration of limonene can be obtained by sampling oil fractions early in HD process; conversely, oil with high concentration of carvone can be obtained by excluding the fractions eluted early in the HD process. We demonstrated a method of obtaining caraway seed oil fractions with various and unique composition. These novel oil fractions with unique composition are not commercially available and could have much wider potential uses, and also target different markets compared to the typical caraway essential oil.