Dairy farmers in the northeast face challenges in the application of manure in fall and on-time planting of cool-season grasses to maximize recovery of residual N and nutrients released from fall applied manure. Ammonia emission from animal manure is a serious environmental concern and can be reduced if cover crop is integrated in the farming system. On-time planting of cover crops can reduce ammonia volatilization from fall, surface-applied manure, and prevents N loss to leaching. A two-year study was conducted in 2015 and 2016 to investigate if time of planting of winter annual rye (Secale cereale L.) along with late fall application of manure when air temperature is low can influence ammonia emission and preserve nitrogen (N) to meet the N requirement of forage rape. Three planting dates (16 September, 30 September, and 14 October) of rye cover crop with two manure application treatments including late-fall application and no manure were assessed for mitigating ammonia volatilization, and also yield and recovery of N by forage rape (Brassica napus L.). The highest rates of ammonia volatilization were detected in the first 24 hours after manure spreading regardless of the treatment. The result indicated that cover crop use significantly limited volatilization compared with no cover crop. The earliest planting date produced 3823 kg ha⁻¹ dry matter of winter rye cover crop that was 16 and 35 percent higher than second and third dates of planting, respectively. The manured cover crop accumulated 132 kg N ha⁻¹ when planted early. However, biomass yield of forage rape was more when planted after all cover crop treatments with manure application. Prior to forage planting, the nitrate-N content in all three soil depths (0–20, 20–40, and 40–60 cm) in the plots with manure was higher than plots with no manure. No significant differences in forage rape yield was detected among winter rye planting dates; however, forage rape planted after winter rye was higher than after no-cover crop. The results of this study suggest that when immediate incorporation of manure into soil is not feasible, establishing cover crop early and then applying manure in the late fall, is a practical management to limit nonpoint source pollution from ammonia loss.

Poor germination and the length of time required for the growth of seedlings appropriate for planting in the farm affect the cultivation of medicinal plants such as yarrow (Achillea millefolium L). This study investigated the abilities of different concentrations of gibberellic acid (GA₃) and potassium nitrate (KNO₃), mechanical scarification, and hydropriming to improve seed germination and dormancy release in yarrow. Seeds were germinated on filter paper in Petri dishes and supplemented with 0, 100, 200, 400, or 800 mg L⁻¹ GA_3; 0%, 0.2%, 0.5%, 1.0%, or 2.0% w/v KNO₃; 0, 24, or 48 h of hydropriming; and mechanical scarification. Seed priming with GA₃ (800 mg L⁻¹) or 1% KNO₃ at 48 h priming time improved the mean daily germination. Application of 1% KNO₃ had the highest seed germination around 91%. Use of 0.5% KNO₃ in 48 h priming time increased seedling length approximately 52% compared with unprimed seeds. Combinations of scarification and hydropriming increased germination. The use of priming with KNO₃ at 48 h priming time was effective in improving seed germination.

The effects of water availability in the soil and fertilizer application often strongly affect crop growth. Tuber dry matter yield and physiological characteristics of potato (Solanum tuberosum L.) were investigated under different irrigation regimes (S₁, full irrigation, 100% of water requirement; S_2, 75% of water requirement; and S_3, 50% of water requirement). Nitrogen treatments were four amounts of urea (N_1, providing 100% of N requirement; N_2, 66% of N requirement; and N_3, 33% of N requirement, and N₄, 0 kg N/ha. Drought stress with 50% of the water requirement and limiting nitrogen fertilizer application suppressed the number and weights of tubers per plant. The yield of marketable tubers in S₁ and S₂ treatments was not significantly different. Treatments N₁, N₂, and N₃ increased the yield of marketable tubers by 37, 33 and 12%, respectively, compared to N₄. Drought stress (S₃) increased the percentage of dry matter, but nitrogen fertilization did not cause a significant change. Drought stress (S₃) increased the amount of soluble sugars in tubers and proline in leaves; however, the amounts of soluble sugars and proline were unchanged by increased nitrogen fertilization. Full irrigation and meeting of nitrogen requirements of potatoes led to high chlorophyll concentrations in leaves. Under drought stress (S₃) and increasing nitrogen, the starch content of tubers was suppressed. The amount of nitrate in the tubers was not affected by irrigation treatments, but was raised by increasing nitrogen fertilization. Irrigation of 75% or more combined with fertilizer application of 66%, was an appropriate treatment for potato production.

This study evaluated vitamin B12 in mitigating freezing stress in thyme (Thymus vulgaris). Treatments included two temperatures (25°C and −5°C) and foliar VB12 application (0 and 100 mg L−1), applied once and twice. Freezing (−5°C) severely damaged roots and reduced shoot biomass by 84%. Although VB12 enhanced growth in non-stressed plants (height: 34 cm, diameter: 63 cm, fresh weight: 232 g), it did not alleviate freezing stress effects. In the absence of VB12, electrolyte leakage increased tenfold under stress, with VB12 having minimal impacts on membrane permeability. A single VB12 application increased Fv/Fm by 31.36%, and non-photochemical quenching declined by 49.5% under freezing. Photosynthetic pigments and chlorophyll stability index increased during stress but declined post-recovery. VB12 application had no effect on malondialdehyde content under stress but reduced levels post-recovery (51.8 and 45.4 μmol g−1 fresh weight for one and two applications, respectively). Hydrogen peroxide levels were 61.16% under stress, decreasing to 56.62% after recovery with one-time VB12 application. These findings suggest that VB12-treated plants’ reductions in electrolyte leakage and reactive oxygen detoxification may improve thyme’s freezing tolerance.