Crop and tillage management effects on water flow and nitrate-nitrogen loss through subsurface drains

Data were collected from subsurface drains on 36, 0.4-ha plots at Iowa State University\u27s Northeast Research Farm near Nashua, IA to determine crop and tillage management effects on water flow and nitrate-N loss through subsurface drains. From 1990 to 1992, four tillage systems (chisel plow, moldboard plow, ridge till and no-till) were used with two crop rotations (continuous corn (Zea mays L.) and corn-soybean (Glycine max L. (Herr.)) rotation) and a single-spring fertilizer application. From 1993 to 1995, tillage systems were reduced to chisel plow and no-till, while fertilizer management changed to include single-spring fertilizer, spring-summer split fertilizer and fall manure application;The amount of nitrate-N lost in subsurface drainage was influenced more by subsurface drainage volume than nitrate-N concentration in drain effluent. Tillage had minimal effects on drainage volume, although no-till plots showed greater preferential flow than chisel plow plots. Significant differences in drain flow only occurred under continuous corn between 1990 and 1992, when the no-till system had higher drain flow than moldboard plow;Tillage affected nitrate-N concentrations in drain effluent during 1990 to 1992. Moldboard plow plots had higher concentrations than no-till plots possibly because of differences in bypass flow, denitrification and mineralization. Nitrate-N concentrations were not influenced by tillage after management systems were changed. However, plots where continuous corn had been grown for 15 yr had higher drain flows and nitrate-N losses in 1993 than where corn was planted into plots that had been rotated with soybean;Nitrate-N concentrations and losses were always higher with continuous corn than with corn-soybean rotation. Corn yields with split fertilizer applications were as high or higher than yields from single application treatments, but nitrate-N losses were essentially the same. Swine manure was difficult to apply at desired rates, resulting in wide variations in yield, nitrate-N concentrations and nitrate-N losses among years. This suggests that manure should be used to supply only a portion of crop nitrogen needs with additional fertilizer added based on late-spring soil nitrate tests

Tillage and crop rotation effects on subsurface drainage response to rainfall

A field study was conducted to determine if tillage and crop rotation affected subsurface drainage response to rainfall. An instrumentation system collected subsurface drain flow data from thirty-six, 0.4 ha plots during the 1993, 1994 and 1995 growing seasons. Response time, time-to-peak drain flow rate, drainage volume, peak drain flow rate and percent preferential flow were compared between two tillage systems (no-till and chisel plow) and two crop rotations (continuous corn and corn-soybean) for 23 drainage events over the three-year study. The influence of preferential flow was estimated for each drainage event using a hydrograph separation procedure based on subsurface drain flow rate changes

Seasonal changes in flow and nitrate-N loss from subsurface drains

Subsurface drainage from thirty-six, 0.4-ha plots was monitored for three years (1990 to 1992) from chisel plow, moldboard plow, ridge till, and no-till systems with continuous corn and corn-soybean rotations. Data were analyzed in four seasonal stages to determine variations in drain flows and nitrate-N contents in drain effluent. The hypothesis of this study was that differences among tillage systems would change during the monitoring season as rainfall patterns varied and as plots were fertilized and cultivated

Alternative N Fertilizer Management Strategies Effects on Subsurface Drain Effluent and N Uptake

Demonstrating positive environmental benefits of alternative N fertilizer management strategies, without adversely affecting crop growth or yield, was a major goal for the Midwest Management Systems Evaluation Areas (MSEA) program. Our project objectives within this program were to quantify the effects of split- and single-N fertilization strategies on NO3-N concentration and loss in subsurface drain effluent and N accumulation and yield of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. The study was conducted on glacial till derived soils in northeast Iowa from 1993 through 1995 using no-till and chisel plow tillage treatments. One-third of the 2,611 effluent samples had NO3-N concentrations greater than 10 mg L–1. Split applying fertilizer N based on pre-sidedress soil nitrate test (PSNT) results significantly increased corn yield for both tillage treatments in the extremely wet 1993 without increasing NO3-N loss in drain effluent. Increased grain yield also resulted in significantly more N removal. When fertilizer N was applied based on the PSNT, no-till and chisel treatments had similar NO3-N losses and concentrations. Average flow-weighted NO3-N concentrations in drain effluent were not increased when larger amounts of fertilizer were applied based on PSNT. However, prior crop and tillage practices and differences in drain flow volume caused significant differences in NO3-N losses and concentrations. These results suggest that spatial differences in flow volume are a major factor determining NO3-N loss in drainage effluent. Significant differences suggest that combining no-tillage practices with split N fertilizer management strategies can have positive environmental benefits without reducing corn yield

Hydraulic modeling of irrigation-induced furrow erosion

In the experimental Version 4.xx series, erosion science is introduced into the surface-irrigation simulation model, SRFR. The hydraulics of water flow in furrows for individual irrigation events is predicted by numerical solution of the unsteady equations of mass and momentum conservation coupled to generally applicable empirical equations describing infiltration and soil roughness and to a known furrow configuration and inflow hydrograph. Selection of appropriate field values for the infiltration and roughness coefficients yields infiltration distributions and surface flows (including runoff) in reasonable agreement with measurements. The erosion component consists in applying the simulated hydraulic flow characteristics to site-specific empirical determinations of soil erodibility, to general empirical sediment-transport relations, and to general physically based deposition theory to provide estimates of soil erosion, flux, and deposition at various points along the furrow as functions of time. Total soil loss off the field and ultimate net erosion and deposition along the furrow follow. At this initial stage of the investigations, a single representative aggregate size is assumed adequate for the analysis. Results are compared to measurements of sediment concentrations in the furrow quarter points and in the tailwater. For a given representative aggregate size, the results are heavily dependent on the choice of transport formula. The Laursen (1958), Yang (1973), and Yalin (1963) formulas are programmed for investigation, as are a variety of computational options. Preliminary comparisons suggest the superiority of the Laursen formulation, with the Yang and Yalin formulas significantly over-predicting transport

Cumulative deficit irrigation and nitrogen effects on soil water trends, evapotranspiration, and dry matter and grain yield of corn under high frequency sprinkler irrigation

Historically feed corn has been a minor crop in south central Idaho, but over the past three decades corn production in southern Idaho has increased fourfold in response to a similar increase in the local dairy industry. Corn seasonal water use and response to water deficits in the region’s climate is lacking. A three-year field study on corn (Zea mays L.) was conducted in 2017, 2018 and 2019 to evaluate the cumulative effects of continuous water and nitrogen deficits on soil water trends, evapotranspiration, and dry matter and grain yield. Four irrigation rates, fully irrigated (FIT) and three deficit irrigation rates (75% FIT, 50% FIT, and 25% FIT) combined with two nitrogen rates (0 and 246 kg N/ha) were investigated under lateral-move irrigation. Growing season soil water depletion in 2017 in the 25% FIT and 50% FIT irrigation treatments significantly reduced soil water availability at planting in subsequent years and resulted in reduced yields relative to 2017. Nitrogen treatments had no significant effect on soil water availability, seasonal soil water depletion, or crop evapotranspiration for a given irrigation treatment. Crop evapotranspiration was significantly different between irrigation treatments in each study year and decreased as irrigation amount decreased. Dry matter yield was significantly different between irrigation treatments in each study year, but there was no significant difference between the 75% FIT and FIT irrigation treatments for a given nitrogen treatment. Differences in dry matter yield decreased between nitrogen treatments as irrigation amount decreased. Grain yield was significantly reduced by deficit irrigation in each study year, but there was no significant difference between the 75% FIT and FIT irrigation treatments for a given nitrogen treatment in study year. Grain yield was significantly different between nitrogen treatments for only the FIT irrigation treatment. The lack of significant difference in grain yield between the 75% FIT and FIT irrigation treatments resulted in a curvilinear convex downward water production response regardless of nitrogen treatment. A reduction in applied water resulted in a reduction of grain yield regardless of nitrogen availability suggesting that a reduction in irrigation application to less productive areas of a field will cause a yield reduction. The lack of significant difference in crop evapotranspiration between nitrogen treatments for a given irrigation treatment indicates that crop evapotranspiration is independent of crop productivity when soil water contents are similar under high evaporative demand and frequent sprinkler irrigation

Conservation tillage effects on sediment and phosphorus losses from a furrow irrigated field

Dry beans are often grown after alfalfa in southern Idaho, which conventionally involves four or more tillage operations before planting. The objective of this three year study (1998-2000) was to determine the effects of conservation tillage on runoff, soil erosion and phosphorus loss from dry beans following small grain under furrow irrigation. Tillage treatments were direct seed, spring disk, fall disk and fall chisel plow. Polyacrylamide (PAM) was applied to half of the furrows during the last two years of the study. Direct seeding increased residue in furrows, which tended to reduce runoff volume and soil loss but increased soluble P loss. Applying PAM significantly reduced soil loss for only 4 of 11 irrigations, but significantly decreased total annual soil loss 63% in 2000. Direct seeding did not significantly reduce dry bean stand, but weed competition and other factors reduced bean yields from direct seed by 39% and 47% the last two years of this study. The three tilled treatments had similar crop yields, residue amounts and phosphorus losse

Advances in Irrigation: Select Works from 2010 Decennial Irrigation Symposium

This paper is an introduction to the Advances in Irrigation Special Collection in this issue of Transactions ASABE and the next issue of Applied Engineering in Agriculture of 14 papers selected from 88 papers and presentations at the ASABE 5th Decennial National Irrigation Symposium, December 2010, in Phoenix, Arizona. This symposium followed the objectives of the previous four decennial events to provide a forum to assess progress of research endeavors to advance the effectiveness of irrigation practices during the past 10 years, leading to further research priorities that respond to future challenges. The papers in this Collection address a wide range of topics grouped into broad categories: microirrigation, center pivot irrigation, crop water use for improved irrigation management, and smart irrigation controllers for landscape irrigation. While these papers are not inclusive of all irrigation work since the last decennial symposium, they do provide a snapshot of work considered important by researchers, funding agencies and other stakeholders. Many aspects of irrigation have changed since the first symposium in 1970. Although microirrigation is a small proportion of irrigated acreage, it will continue to increase in highly technical commercial food and fiber production as well as in subsistence farming. Center pivot irrigation systems have been an important tool to deliver water more efficiently in diverse settings. Advanced telemetry and control systems, developed during the past 10 years, are now common options for center pivots, but challenges remain to integrate those hardware developments into crop management practices. Possibilities are emerging for adding monitoring devices to center pivots to match crop water needs with water delivery. Energy balance models continue to be refined as tools to estimate crop water use from both ground and satellite based data. Evapotranspiration estimates are evolving from single location weather stations to whole-field or regional scopes. Finally, “smart” irrigation controllers have coupled evapotranspiration estimation or soil-water sensing with automated irrigation system water delivery. These controllers can increase the precision of irrigation to match crop or landscape water needs. Irrigation will continue to be an important practice for producing the world’s food. The irrigation research and education professions will need to respond to food production challenges with even more refined irrigation systems and water management in the next 10 years. However, research investment in irrigation continues to decline when important issues exist, such as: maintaining agricultural profitability with declining water supplies, integrating sensor-based information for real-time autonomous or semi-autonomous management, competition for limited water supplies between agriculture and other sectors, increasing energy cost, environmental impacts of irrigation, and use of alternative water sources (i.e., lower quality) for irrigation

Using polyacrilamide with sprinkler irrigation to improve infiltration

ABSTRACT: Center-pivot irrigation systems often apply water at rates greater than the soil infiltration rate. Applying high molecular weight, water-soluble, anionic polyacrylamide (PAM) to the soil can improve infiltration and reduce soil erosion The objective of this study was to determine whether single and multiple PAM applications with sprinkler irrigation improved infiltration under field conditions. A two-year study conducted near Kimberly, Idaho, used a solid-set sprinkler system, and a one-year study conducted in Monte dos Alhos near Alvalade do Sado, Portugal, used a center pivot. At Kimberly, applying PAM with four irrigations (total applied PAM was 2.1 kg ha−1 in 2000 and 3.0 kg ha−1 in 2001) significantly reduced total measured runoff, from 5.9 mm (2000) and 9.2 mm (2001) for the control to 2.0 and 2.1 mm. Total measured soil erosion was also reduced from 52 and 34 kg ha−1 for the control to 21 and 5 kg ha−1 for the multiple PAM treatment. Applying similar or greater amounts of PAM with a single irrigation reduced erosion, but not runoff, compared with the control. In the Monte dos Alhos study, runoff was reduced by applying a total of 0.3 kg PAM ha−1 with a single irrigation (43 mm runoff) or three irrigations (65 mm runoff) compared with the control (111 mm runoff). Measured soil erosion was not significantly different among treatments. Applying PAM with multiple irrigations extended its effectiveness as long as the application rate was great enough to adequately stabilize the soil surface during the first irrigation

Sprinkler irrigation runoff and erosion control with polyacrylamide - laboratory tests

Many semiarid and arid soils are prone to irrigation-induced erosion. Polyacrylamide (PAM) greatly reduces erosion from furrow irrigation. We hypothesized that PAM applied via sprinklers will provide erosion control and benefit water infiltration and aggregate stability. Screened (6.4 mm) Rad silt loam (coarse silty, mixed, superactive mesic Durinodic Xeric Haplocambid) was placed in 1.5 by 1.2 by 0.2 m steel boxes with 2.4% slope. An oscillating nozzle, 3 m above the soil, produced a median drop size of 1.2 mm diameter. We applied 0, 1, 2, 4, and 6 kg ha-1 PAM in 20 mm of water in the first irrigation, followed by two 20-mm water-only irrigations. In a second test, we applied 0, 2, and 4 kg ha-1 PAM in 8 mm of water in the first irrigation, followed by two 20-mm water-only irrigations. Two kilograms per hectare PAM in the first 20-mm irrigation reduced runoff 70% and soil loss 75% compared to control. Polyacrylamide in 8 mm of water was less effective. Polyacrylamide in the 20-mm irrigation did not affect tension infiltration; PAM in the 8-mm irrigation doubled tension infiltration following the third irrigation. Wet aggregate stability following the first irrigation was greater in all PAM treatments than on the check. With 2 kg ha-1 PAM in the 20-mm irrigation, it was 55%; in 8 mm, 77%. Polyacrylamide applied in the first irrigation at low rates effectively reduced runoff and erosion. Erosion was more effectively controlled than runoff