Clain Jones

Response of Malt Barley to Phosphorus Fertilization Under Drought Conditions

ABSTRACT Drought conditions are common in the northern Great Plains of the United States, affecting crop yield and quality. Phosphorus (P) fertilizer applications have been found to increase drought tolerance, although there is a lack of published work in this area. The goal of this study was to determine the effects of P fertilization on drought tolerance in malt barley (Hordeum vulgare). Here, 60 cm tall PVC columns were filled with either a silt loam that had a medium soil test phosphorus (STP) level or with the same soil diluted 1:1 (v/v) with coarse sand (low STP). Monoammonium phosphate was incorporated into the surface soil at rates equating to 0, 7.5, and 25 kg P ha− 1 (in triplicate), seeded with malt barley, and watered to maintain water contents either slightly above –1.5 MPa (dry treatment) or slightly drier than field capacity (wet control). Fertilization with P significantly increased plant biomass, root biomass, grain yield, and water-use efficiency (WUE) in the medium STP soil, but not in the low STP soil. Growth in the low STP, coarse, dry soil was apparently limited by water, not P, based on comparisons with the wet control. Fertilization of the dry medium STP soil with P increased grain yield by at least 20-fold, although this increase was not significant due to high variability. These results suggest that adequate soil P levels can substantially offset the impact of drought on barley growth and grain yield.

Effect of Low‐Rate Commercial Humic Acid on Phosphorus Availability, Micronutrient Uptake, and Spring Wheat Yield

Abstract A greenhouse study was conducted to determine the effects of low‐rate commercial humic acid (HA) on phosphorus (P), iron (Fe), and zinc (Zn) availability and spring wheat yields, in both a calcareous soil and a noncalcareous soil. In Phase I, soluble P concentrations were monitored at 1.9, 3.8, and 5.7 cm from a monoammonium phosphate (MAP) fertilizer band that had either been coated with one of two HA products at the equivalent of 1.7 kg HA ha−1, a label rate, or left uncoated. Sampling occurred periodically up to 48 d after fertilizer application. In Phase II, uptake of P, Fe, and Zn and grain yield were measured in soils that had been fertilized with 7.5 or 25 kg P ha−1, either coated with HA or left uncoated. In Phase I, only three significant differences (P=0.05) out of 66 comparisons were found in soluble P concentrations between HA and control treatments at time points ranging from 4 to 48 d after fertilization. In addition, no significant differences were found in nutrient uptake, shoot biomass, or grain yield between HA and control treatments. These greenhouse results suggest that low commercial HA rates (∼1.7 kg HA ha−1) may be insufficient to enhance spring wheat growth.

Metal concentrations in three Montana soils following 20 years of fertilization and cropping

The presence of metals in some agricultural fertilizers has raised the concern that fertilized soils may be accumulating potentially toxic metals. A number of studies have been undertaken to determine the extent and significance of this potential problem, yet results have been mixed and the studies were not conducted in the Northern Great Plains. Therefore, a study was undertaken to determine if fertilization has increased metal concentrations in selected Northern Great Plain soils. Two irrigated sites and one non-irrigated site were selected; each had at least 20 years of fertilization and cropping history. Paired (fertilized and non-fertilized) soils from three depths (0–15 cm, 15–30 cm, and 30–45 cm) were sampled in replicate (n=10) and analyzed for a range of plant available and total metals, pH, organic matter, and phosphorus. In general, fertilized soils were found to have significantly lower levels of available and total metals than those of non-fertilized soils, indicating that long-term fertilization has not increased metal concentrations in the soils studied.

Pulse Crops Improve Energy Intensity and Productivity of Cereal Production in Montana, USA

Energy consumption, intensity, and productivity are indicators of agricultural sustainability in the face of fossil energy scarcity and price volatility. In this study, budgets of energy embodied in crop production inputs were compiled for 14 paired pulse (annual grain legume)-wheat and wheat-wheat crop sequences using data collected from Montana farmers. We report two energy performance metrics: net energy yield (NEY), the energy content of harvested crop minus energy required to produce it, and energy intensity (EI), the ratio of input energy to mass of crop harvested. Nitrogen fertilizer accounted for 58% of the energy used in wheat production, and its absence largely accounted for the 53% reduction in energy inputs to pulses relative to wheat. EI of pulses was lower than for wheat, and pulse crops also resulted in reduced EI and increased NEY for the subsequent wheat crop compared to wheat grown following wheat. The largest component of the improved energy performance of wheat following pulses was increased yield rather than decreased inputs.

Identifying Linkages Between Land Use, Geomorphology, and Aquatic Habitat in a Mixed-Use Watershed

The potential impacts of land use on large woody debris (LWD) were examined in Sourdough Creek Watershed, a rapidly growing area encompassing Bozeman, Montana, USA. We identified six land classes within a 250 m buffer extending on either side of Sourdough Creek and assessed aquatic habitat and geomorphologic variables within each class. All LWD pieces were counted, and we examined 14 other variables, including undercut bank, sinuosity, and substrate composition. LWD numbers were generally low and ranged from 0 to 8.2 pieces per 50 m of stream. Linear regression showed that LWD increased with distance from headwaters, riparian forest width, and sinuosity in four of the six land classes. Statistically significant differences between land classes for many aquatic habitat and geomorphologic variables indicated the impacts of different land uses on stream structure. We also found that practices such as active wood removal played a key role in LWD abundance. This finding suggests that managers should prioritize public education and outreach concerning the importance of in-stream wood, especially in mixed-use watersheds where wood is removed for either aesthetic reasons or to prevent stream flooding.

Variation in soil fertility test results from selected northern great plains laboratories

Soil analytical labs play an important role in agricultural nutrient management. However, variability between labs can undermine the perception of soil testing efficacy and possibly lead to inaccurate fertilizer recommendations. To compare standard soil analysis results from labs commonly used by Montana producers, soil samples from four different sites were sent anonymously to up to ten labs over a three year period, with three submissions per year. Variability within labs and between labs was observed, and is at least partially linked to different laboratory methods or changes in laboratory methods during the study period. Several labs showed a trend of improving lab repeatability. The results suggest that agricultural professionals should choose their labs wisely, specify analytical methods, and review results critically. In addition, the analytical data reported, and ultimately, the fertilizer recommendations provided, should be considered guidelines to nutrient management to be tailored to site-specific conditions.

Effects of Dust Control Coatings on Phosphorus Fertilizer Dissolution and Uptake

Granular phosphorus (P) fertilizers are often treated with coatings, such as oil or wax, to decrease dust production during packaging, shipping, storage, and spreading. Unconfirmed reports from the field suggest these coatings may negatively impact plant response to applied P fertilizers. A three-phase study was conducted to determine if these coatings significantly affect P dissolution rates, soil P test levels, P uptake, or yield. Coated and uncoated monoammonium phosphate granules were obtained from two fertilizer manufacturers. In Phase I, fertilizer dissolution rates in water were measured for fertilizer application rates representing both irrigated and dryland conditions. In Phase II, dissolution rates were evaluated in an acid-washed sand at two moisture contents. In Phase III, Olsen P, P uptake, and dry biomass in corn were measured in a low pH and high pH soil for both broadcast and incorporated fertilizer applications. Dust control coatings did not significantly decrease dissolution rates, Olsen P levels, P uptake amounts, or biomass for any of the treatments or at any time. In a small percentage of comparisons, coatings significantly increased solubility, Olsen P levels, P uptake, or biomass; although, in general, coatings caused no significant differences in these parameters.

Ammonia volatilization losses were small after mowing field peas in dry conditions

Engel, R., Jones, C. and Wallander, R. 2013. Ammonia volatilization losses were small after mowing field peas in dry conditions. Can. J. Soil Sci. 93: 239-242. Ammonia losses following termination of peas (Pisum sativum L.) by mowing were measured using a micrometeorological mass-balance approach. Field trials were conducted during two seasons in a semiarid climate. Plant N in the above ground biomass was 105 and 79 kg N ha-1 in 2011 and 2012, respectively. Vertical NH3 flux estimates were nominal (0.3 to 1.7 g N ha-1 h-1) in the 2 wk following mowing. Cumulative NH3 loss represented 0.3 to 0.5% of the N in plant biomass, indicating that N fertility was not diminished by NH3 volatilization in this dry climate.