January - February 2006: Volume 61, Number 1

Table of Contents

Features
The Vanishing Prairie
By Clay Ogg

Seeing the Trees Along the Streamside
By William A. Lakel, III, W. Michael Aust and C. Andrew Dolloff

What We Don't Know Can Hurt Us
By Laura M.J. McCann, Jennifer Twyman Nunez and Peter Nowak

Research

Departments

• Homefront—Looking Forward
• Raise Your Voice
• Viewpoint—Waters importance in the future
• Notebook
• Editor's Choice
• Conservogram

ABSTRACT: Commercially-available inorganic fertilizers are often used by beef and dairy producers to increase forage growth on perennial pastures and hay fields, but the usual practice of spreading fertilizer granules on the surface of these grasslands leaves the nutrients exposed for transport in runoff, and for rapid nitrogen (N) loss to the atmosphere as ammonia. We hypothesized that such problems could be minimized by using a knifing technique to move the fertilizer granules into the subsurface root zone of perennial forages, and conducted a study to determine the effect on runoff water quality. Plots were constructed on a hillside (8 to 10 percent slope) field with a silt loam soil covered by well-established bermudagrass [Cynodon dactylon (L.) Pers.] and mixed grass forage. Each plot had borders to isolate runoff and a downslope trough with sampling pit for collection. Inorganic 13-13-13 fertilizer granules were applied at 1.34 Mg ha-1 (0.6 t ac-1) by one of three methods: surface spreading, incorporation, or surface spreading on soil cuts. Each treatment had six replications and there were three control plots that were not fertilized. Runoff samples from simulated rainfall applied at 50 mm h-1 (2 in hr-1) and natural rainfall events showed that nutrient losses in runoff from incorporated fertilizer were statistically no higher than from control plots, but were usually at least 90 percent less than those from surface-applied fertilizer. Soil cuts slightly decreased nutrient losses from surface-applied fertilizer, but this effect was rarely significant. When compared to surface-applied fertilizer, the incorporated fertilizer not only improved water quality, but also showed a strong tendency to increase forage yield.

Keywords: Fertilizer incorporation, nutrient management, perennial pasture, runoff water quality

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ABSTRACT: Soil coverage by residue protects soil and land resources from erosion, conserves soil water, and maintains soil quality. No-till and chemical weed control are management practices that increase soil coverage by residue. On the other hand, crop diversification in dryland agriculture in the northern Great Plains promotes the use of crops that produce significantly less soil coverage by residue than small cereal grains. Within a 10 x 10 crop sequence project under no-till in south-central North Dakota [409 mm (16.1 in) mean annual precipitation], all two-year crop sequence combinations of ten crops (barley, canola, crambe, dry bean, dry pea, flax, safflower, soybean, spring wheat, and sunflower) were evaluated at two adjacent sites. Soil coverage by residue was measured by transect and photographic techniques following spring wheat seeding. Soil coverage ranged from 98 to 89 percent following crop sequences that included spring wheat and barley. Soil coverage values were intermediate for spring wheat—alternative crop sequences, 97 to 62 percent. Crop sequences not including spring wheat with alternative crops for two years had values ranging from 86 to 35 percent. Soil coverage values after two consecutive years of sunflower or dry pea (two years of data) and two years of dry bean or safflower (single year of data) were in a lower range, 48 to 35 percent. Soil erosion hazards were evaluated with equations based on residue effects alone that were taken from the Revised Universal Soil Loss Equation (RUSLE) water erosion and Revised Wind Erosion Equation (RWEQ) wind erosion models: calculated soil loss ratio values (SLR = 1 with no residue protection) for 35 percent coverage following a sunflower-sunflower sequence were 0.29 for water erosion and 0.21 for wind erosion. Even with use of no-till, especially on more fragile soils, producers should consider planting a higher residue-producing crop (e.g., wheat, flax) the year before seeding lower residue-producing crops in order to assure adequate protection of soil and land resources.

Keywords: Crop residue, diverse cropping system, no-till, water erosion, wind erosion

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No-till cultivation improves stream ecosystem quality

A.G. Yates, R.C. Bailey, and J.A. Schwindt

ABSTRACT: No-till cropping systems have become very common in North America over the past two decades. The effects of no-till on stream quality, however, have not been studied at watershed scales. We measured habitat and stream water quality and sampled the benthic macroinvertebrate community in 32 small (100 to 1400 ha, 247 to 3,460 ac) subwatersheds that exhibited a gradient of the proportion of land under no-till cropping systems to determine relationships between the use of no-till and stream quality. Increased use of no-till systems resulted in improvements in habitat and water quality and the benthic macroinvertebrate community. Based on these results we concluded that increased use of no-till cropping systems by farmers has a positive effect on the quality of streams in agroecosytems.

Keywords: Benthic macroinvertebrates, habitat, southern Ontario, stream quality, tillage systems, no-till, m-basin, water quality

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ABSTRACT: The phosphorus (P) index is the preferred method of implementing P-based nutrient management plans in Pennsylvania. The P index is a field level risk assessment tool that quantifies P source and transport factors to determine if management changes are necessary to avoid off-site transport of P to surface waters. It is important for conservation officials to understand the effect P restrictions will have on farms and farming communities. This study applied the P index to 276 fields on 13 farms in two Pennsylvania counties, Lancaster and Snyder, which were previously identified as having the potential to face severe restrictions under P-based nutrient management. Of all soil samples, 18 percent exceeded the 200 ppm environmental soil P threshold which triggers full assessment under the P index. Lancaster County had significantly greater soil P test levels compared to Snyder County. Trends of increased soil P test and increased P restriction were observed as animal density increased. Additionally, soil P levels on land with animal concentration areas exhibited significantly greater soil P, compared to cropland and pastures. Preliminary screening based on soil test P levels and proximity to water, indicated that full P index assessment was required for 46 percent of the fields in Lancaster County and 19 percent of the fields in Snyder County. This indicates that Lancaster will face greater nutrient management planning costs. After applying the full P index, Lancaster and Snyder Counties had 31 and 12 percent of the fields P restricted, respectively. Four highly impacted farms were closely examined to determine the feasibility of complying with P restrictions. Two farms were able to comply with on-farm options, and two required a solution that would require moving P offsite. Farms studied were representative of localities where animal agriculture is a critical part of the economy. The large proportion of fields restricted under the P index—20 percent of all fields studied—indicates that technical and financial assistance may be required to allow these operations to remain economically viable. Additionally, conservation officials need to be mindful of the need for long-term solutions that address the fundamental problem of regional nutrient surpluses.

Keywords: Eutrophication, nonpoint source pollution, nutrient management, phosphorus, P index

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ABSTRACT: Recent evidence suggests that turfgrass nutrients in runoff and subsurface flow pose potential risks to surface water quality. Research on water quality associated with turfgrass has generally focused on surface runoff, not subsurface flows. Quantifying the delivery of nutrients, nitrate nitrogen (NO3-N) and dissolved reactive phosphorus, to streams from subsurface drainage features on managed turf sites, and relating the transport to fertility management and season is important for many urban managers, especially those under regulatory scrutiny. NO3-N and dissolved reactive P concentrations from two French drains located on the Morris Williams’ Municipal Golf Course in Austin, Texas, were measured over a four-year period (March, 1999 to March, 2003). Time series statistics were used to analyze and relate NO3-N and dissolved reactive P concentrations to weather and management. A weak statistical relationship (r2 = 0.55) was detected between discharge and NO3-N concentration at one of the two drains. The relationship between discharge and dissolved reactive P concentration was not significant. Median NO3-N concentrations from the two drains were 1.27 mg L-1 and 0.32 mg L-1. NO3-N loading from the drains was 2.7 kg ha-1 (2.4 lb ac-1). The NO3-N concentrations and load from the turf area were approximately 10 percent of those values reported for typical row crop agriculture. Median dissolved reactive P concentrations were 0.11 mg L-1 and 0.09 mg L-1 while dissolved reactive P loading was 0.46 kg ha-1. Significant (a = 0.05) seasonal tendencies were found with respect to NO3-N and dissolved reactive P. A strong correlation was evident between the timing of peak NO3-N losses and nitrogen application; and between the timing of peak NO3-N losses and air temperature. There was a similar correlation between the timing of peak dissolved reactive P losses and phosphorus application. Our results suggest NO3-N transport in subsurface drainage from this golf course is not a water quality issue. However, our findings suggest significant dissolved reactive P transport through the drains and a need for an integrated (turf, nutrients, and water) management plan that includes consideration of subsurface drainage fluxes.

Keywords: Golf course, nutrients, time series, urban, water quality

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ABSTRACT: Conventional management practices for the rice-wheat rotation in Pakistan’s Punjab have failed to improve crop yield, increase water and fertilizer use efficiencies, and decrease production costs enough to meet an ever-increasing food demand. New technologies such as no-till, laser leveling, and bed and furrow irrigation are being rapidly adopted by the farming community, but without adequate scientific information. Therefore, those practices were evaluated on 71 farms within four representative sites. Land preparation/sowing costs, water savings, use of fertilizers, soil salinity, and crop yield were evaluated. Land preparation and sowing cost on no-till fields was significantly less than on tilled fields. Highest yields were obtained on laser-leveled fields, followed by no-till, bed and furrow fields. Water and nitrogen use efficiencies were much higher on fields with bed and furrow irrigation as compared to the conventional fields. Although all the new technologies were economically feasible, we conclude that no-till was the best option for the farmers.

Keywords: Bed and furrow irrigation, laser leveling, nitrogen use efficiency, no-till, Pakistan, soil organic matter, water use efficiency

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