Assessing Sulfur Fertilization as a Means to Improve Statewide Forage Quality and Value by Reducing Nitrate Accumulations in Cereal Forages
Project Title:
Assessing Sulfur Fertilization as a Means to Improve Statewide Forage Quality and Value by Reducing Nitrate Accumulations in Cereal Forages
Objective:
Assessing forage barley to reduce nitrate accumulations and improve forage quality.
Personnel:
Daniel Porter, Marilyn Dalen, Amanda Grube, Hayes Goosey, J.A. Torrion, Clain Jones, Patrick Carr, Kent McVay, Perry Miller, Jamie Sherman
Summary:
This project was part of the multi-location study in Montana. In Creston, Lavina forage barley was planted with nine different levels of nitrogen and sulfur fertilizer rate combinations. See Table 1 for management information.
Yield, total digestible nutrients (TDN), crude protein (CP), nitrate (NO-3), and ground cover percentage increased overall while neutral detergent fiber (NDF) decreased with increasing soil nitrogen and sulfur in the soil. Medium to high N and high S treatments had higher yield with lower nitrate concentrations. Concentrations of nitrate between both medium N treatments with both medium and high S, decreased but did not decrease with High N treatments regardless of the level of sulfur applied. In regards to safe levels of nitrate for feed, the recommendation based on this data is a range from generally safe for non-pregnant livestock and limiting feeding to 50% of the total ration for bred animals for medium N levels (1,500 – 5,000 ppm) to not limiting feeding pregnant livestock and also having a limit of 25-50% rations for non-pregnant livestock (Goosey et al., 2022). The 2023 data suggests that medium levels of N and medium levels of sulfur will maximize yield, NDF, TDN, and minimize nitrate levels, which can reduce input costs and increase barley forage quality. See Table 2 for total agronomic performance.
Generally speaking, at the NWARC (Table 1) most notably we report that 10 lbs./acre and 20 lbs./acre sulfur rates reduced nitrate in medium (1.0 X) and high (1.5 X) nitrogen treatments. Medium nitrogen and high sulfur yielded higher than high nitrogen and sulfur and also had lower nitrate concentrations.
Table 1. Management Information |
|||
| Seeding date: | 4/24/2023 (114 Julian) | Field Location: | D1 |
| Seeding rate: | 25 seeds/ft2 | Harvest date: | 8/7/2023 (216 Julian) |
| Previous crop: | Canola | Soil type: | Creston Silt Loam |
| Herbicide: | CleansweepM 1pt/A, Axial Bold 15oz/A | Tillage: | Conventional |
| Insecticide: | N/A | Soil residual nutrient (NO3-, P, K lb/A): | 35.5-30-223 (Fall, 2022) |
| Fungicide: | N/A | Nutrient fertilizer applied (N, P2O5, K2O lb/A): | See Table 2 |
Table 2. Crop yield and quality response of forage barley fertilized with low, medium, and high nitrogen and sulfur rates at the Northwestern Agricultural Research Center during 2023, where letter groups represent significant treatment effects
1TRT = treatments where Low N = 21 lbs. acre-1 (0 lbs. N acre applied + 21 lbs. N acre-1 residual), Medium N = 227.5 lbs. acre-1 (206.5 lbs. acre-1 applied + 21 lbs. acre-1 residual), High N = 341.25 lbs. N acre-1 (320.25 lbs. N acre-1 applied + 21 lbs. acre-1 residual); Low S = 0 lbs. acre-1, Medium S = 10 lbs. acre-1; High S = 20 lbs. acre-1.
2NDF = neutral detergent fiber, an estimate of forage bulk fiber where lower values equate to higher digestibility and animal intake.
3DDM = digestible dry matter, an estimate of forage digestibility where higher values equate to higher energy value forage, calculated as DDM = 88.9 - (0.779 * ADF%).
4CP = crude protein, an estimate of forage total nitrogen where higher values equate to higher forage nitrogen.
5Nitrate = = Converted from % nitrate to ppm. <1,500 is considered safe for all livestock. 1,500 – 5,000 ppm is generally considered safe for nonpregnant livestock, limit bred animals 50% of total ration. 5,000 – 10,000 ppm should not be fed to pregnant animals, limit non-bred animals to 25-50% of total ration.
6Tissue S = percent plant tissue sulfur
7Tissue N = percent plant tissue nitrogen
8NDVI = normalized difference vegetation index. An estimate of plant health as a measure of near infrared and red wavelength reflectance from plant tissue. (NIR-Red)/(NIR+Red) = NDVI