Deep Silt Loam Soil Research Articles

Cotton Response to Irrigation and Nitrogen Source in Differing Mid‐South Soils

Core IdeasCotton yield and N uptake are examined across irrigation regimes, N sources, and soils.In two wet growing seasons, cotton in silt loam soils did not respond to irrigation.Cotton in coarse‐textured soils required irrigation beginning at bloom in wet years.Use of controlled release N resulted in generally lower yields than ammonium nitrate.In coarse‐textured soils, cotton yielded similarly between N sources.Cotton (Gossypium hirsutumL.) irrigation management is challenging in a humid region, where rainfall is unpredictable and soils range from coarse‐textured to fine‐textured. Loss of applied N in coarse‐textured soils receiving high amounts of irrigation is a concern for producers. This study was conducted to improve cotton irrigation recommendations in differing soils in the Mid‐South and to evaluate the effect of a controlled release N fertilizer on N uptake and yield of cotton grown in different soils and irrigation regimes. The effects of irrigation initiation/rate and N source on cotton yield and N uptake were investigated in Jackson, TN, in soils that differed in texture. In two wet growing seasons, cotton grown in deep silt loam soils did not respond to irrigation. Irrigation of cotton grown in coarse‐textured soil could be delayed until bloom without yield loss, but then needed a supplemental rate of 38.1 mm wk−1to optimize yield. These results reveal a clear benefit to managing irrigation separately in differing soils, when possible. Cotton receiving ammonium nitrate (AN) generally yielded higher than cotton receiving controlled release N fertilizer. However, cotton yields were similar between N sources in coarse‐textured soils. Our results support the notion that cotton grown in differing soils would benefit from multiple irrigation decisions, and indicate no apparent yield or N uptake benefit from the use of a controlled release N fertilizer in no‐till cotton.

Yield and Soil Water in Three Dryland Wheat and Grain Sorghum Rotations

Core Ideas Grain yield of the second wheat crop was 80% of first wheat crop in WWSF. Grain yield of the second sorghum crop was 63% of first sorghum crop in WSSF. Four‐year rotations were similar in productivity to 3‐yr WSF. Water productivity was greater with 4‐yr rotations than continuous wheat. Continuous no‐till did not increase second year wheat and sorghum yields. Diverse crop rotations sustain crop productivity by increasing crop water productivity and improving soil structure. The objective of this study was to compare two 4‐yr winter wheat (Triticum aestivum L.) and grain sorghum (Sorghum bicolor L.) rotations in terms of grain yield, available soil water, and water productivity along with continuous winter wheat. A field study was conducted from 1996 through 2015 on a deep silt loam soil near Tribune, KS. The study consisted of three crop rotations: continuous annual wheat (WW), wheat–wheat–sorghum–fallow (WWSF), and wheat–sorghum–sorghum–fallow (WSSF). Grain yield, biomass, water productivity, and soil water were all greater for sorghum after wheat compared with sorghum after sorghum. Similarly, grain yield, biomass, water productivity, and soil water were all greater for wheat after fallow compared with wheat after wheat. The yield of the second wheat crop was 80% of the first wheat crop in WWSF, whereas the yield of a second sorghum was only 63% of the first sorghum crop in WSSF. The average crop water productivity (7 kg ha−1 mm−1) of the WSSF rotation was greater than the other rotations. On average, the WSSF system produced 2.05 Mg ha−1 yr−1 wheat equivalent yield (WEY), which was similar to the 1.96 Mg ha−1 yr−1 WEY from the WWSF rotation and greater than WW, which produced 1.53 Mg ha−1 yr−1 of wheat grain. A WSF rotation would have produced 2.0 Mg ha−1 yr−1 WEY, so the 4‐yr rotations were not more productive than a 3‐yr WSF rotation.

A Deficit Irrigation Trial in Differing Soils Used To Evaluate Cotton Irrigation Scheduling For The Mid-South

Cotton (Gossypium hirsutum L.) irrigation management in the humid Mid-South is complicated by unpredictable rainfall and significant soil variability. Producers of irrigated cotton need guidance with making irrigation decisions to create conditions for optimal yield while efficiently managing irrigation water use. The objectives of this study were to demonstrate cotton yield response to varying irrigation across differing soils and to evaluate the ability of a water balance approach, and the use of soil moisture sensors to guide sound irrigation decisions. A three-year study was conducted in Jackson, TN where cotton was grown on soils ranging from primarily sandy-textured to deep silt loam soils and was drip-irrigated under several irrigation regimes. Three years of differing rainfall patterns demonstrated a need for different irrigation management between soils to optimize cotton yield each year. Sandy soils needed irrigation at a higher rate each year and an earlier initiation two of three years. A deficit between applied water and crop water use was especially important in silt loam soils, which required more judicious application of irrigation. A water balance approach to irrigation scheduling was a good indicator of soil and crop water status in sandy and silt loam soils. Soil moisture sensors often reflect the status of the water balance, however, in some cases soil moisture sensors could have triggered unnecessary irrigation based on suggested irrigation thresholds. While each method of irrigation scheduling has shortcomings, using a water balance in conjunction with soil moisture sensors is recommended, such that each can verify the other.

Limited Irrigation of Corn‐Based No‐Till Crop Rotations in West Central Great Plains

Identifying the most profitable crop rotation for an area is a continuous research challenge. The objective of this study was to evaluate 2‐, 3‐, and 4‐yr limited irrigation corn (Zea mays L.)‐based crop rotations for grain yield, available soil water, crop water productivity, and profitability in comparison with 1 yr continuous corn (CC). A field study was conducted from 2001 through 2010 on a deep silt loam soil near Tribune, KS. The study consisted of four crop rotations, that is, CC, corn–winter wheat (Triticum aestivum L.) (C–W), corn–winter wheat–grain sorghum (Sorghum bicolor L.) (C–W–Gs), and corn–winter wheat–grain–sorghum–soybean [Glycine max (L.) Merr.] (C–W–Gs–Sb) with irrigation limited to 254 mm annually. Grain yield of corn from the CC rotation was significantly lower, on average by 2.5 Mg ha−1, than corn yield from the other three rotations mainly due to difference in irrigation level. However, the mean yield of CC over one cycle of rotation [∼10.2 Mg (ha rotation‐cycle)−1] was significantly greater than mean corn equivalent grain yield of the other three rotations over one cycle of each rotation. Seasonal soil water usage from upper depths of the soil profile was significantly greater for CC. In this study, average crop water productivity [16.6 kg (mm ha)−1] and profitability of the CC rotation were also greater than in the other rotations. In selecting profitable rotations, producers should consider crop yield potential and value in addition to resilience.Core Ideas This research compares four corn‐based rotations from yield, resource use, and impact on environment which are crucial to cropping decision and consulting Second it addresses an area of limited water irrigation condition in which research outputs are rare. Dryland and irrigated conditions are relatively well covered, but cropping decision when there is resource which is more than dryland but less than full irrigation is not well addressed. This research result contributes to that. Third, this research is based on long‐term data that address yield of major crops (corn, wheat, sorghum, and soybean) and water use of these crops at every 30 cm of rooting depth. This information will continuously be used by researchers looking for such a data for modeling and other purposes.

Six crop models differ in their simulation of water uptake

Root water uptake is an essential component of crop models since it affects plant growth and, through its effect on the soil water balance, multiple soil and nutrient cycling processes. Several methods to simulate water uptake exist; however, the differences among them have not been evaluated. We compared the water uptake methods implemented in six crop models: APSIM, CropSyst, DSSAT, EPIC, SWAP and WOFOST. These methods range from simple empiric approaches (WOFOST) to mechanistic approaches based on the water potential gradient and root distribution in the soil–plant system (CropSyst). We compared the six models’ water uptake algorithms in scenarios with different evaporative demand, soil texture, and water distribution with depth. The main difference among methods derived from the degree to which each model enabled the use of water in the subsoil (below 0.5m). In a rooted, 1-m deep silt loam soil in which the root density decreased geometrically with depth and which was subjected to an evaporative demand of 5mmd−1 for 60 days, APSIM, EPIC, DSSAT and SWAP transpired about 83% of the total plant available water while SWAP and CropSyst transpired about 65% of it. When methods were compared with initially dry bottom soil layers, cumulative transpiration became similar for all methods, while the opposite initial condition exacerbated differences. All methods, except CropSyst, increased transpiration as the evaporative demand rose to relatively high rates (10mmd−1) because they lack a feedback mechanism that reduces transpiration when the demand exceeds the plant's ability to conduct water. CropSyst, DSSAT, EPIC and SWAP developed a drying front, as usually observed in field conditions, while APSIM and WOFOST showed relatively uniform water depletion with depth in the soil profile. In conclusion, the models differ meaningfully in their simulation of water uptake and careful consideration of these differences is needed to properly use and interpret the outcome of model simulations.

Corn Production: A Subsurface Drip Irrigation Approach

Jilin Provincial Academy of Agricultural Machinery initiated studies in 2000 to develop the methodology for successful application of subsurface drip irrigation (SDI) for corn production on the deep silt loam soils of the northeast plains, China. Irrigation water use for corn can be reduced by 37–52% when using SDI compared with more traditional forms of irrigation in the region. Irrigation frequency has not been a critical issue when SDI is used for corn production on the deep silt loam soils of the region. A dripline spacing of 1.5 m has been found to be most economical for corn grown in 0.76 m spaced rows. Nitrogen fertigation was a very effective management tool with SDI, helping to maximize corn grain yield, while obtaining high efficiencies of nitrogen and water use. The research SDI systems have been utilized since 2000 without replacement or major degradation. SDI systems lasting 10–20 years are cost competitive for corn production with the more traditional forms of irrigation in the northeast plains for certain field sizes.

Alfalfa Production with Subsurface Drip Irrigation in the Central Great Plains

Irrigated alfalfa production is gaining interest because of the growing number of dairies in the semi-arid U.S. Central Great Plains and its longstanding superior profitability compared to other alternative crops grown in the region. Irrigation requirements for alfalfa are great because of alfalfa’s long growing season, so it is important that irrigation be utilized efficiently in this region where water is pumped from the declining Ogallala aquifer. A three-year yield study (2005-2007) was conducted at the Kansas State University Northwest Research-Extension Center in Colby, Kansas, to evaluate production of subsurface drip irrigated alfalfa on a deep productive silt loam soil. Three irrigation levels (randomized complete block design of three replications) designed to replace 70%, 85%, or 100% of the calculated crop evapotranspiration minus precipitation were compared in terms of alfalfa yield, irrigation amount, plant-available soil water, crop water use, and crop water productivity. Alfalfa yield was also evaluated at three perpendicular horizontal distances from the 1.5 m spaced driplines (0, 0.38, and 0.76 m). Annual alfalfa yields were unaffected by irrigation level, averaging 20.8 Mg ha-1 while irrigation amounts averaged 396, 484, and 586 mm for the 70%, 80%, and 100% ET irrigation levels, respectively. Seasonal crop water use was significantly greater with increased irrigation, but only by an average difference of 137 mm among irrigation levels as compared to the 190 mm difference in irrigation amount. Crop water productivity was significantly greater with decreased levels of irrigation, with values of 23.5, 22.0, and 20.4 kg ha-1 mm-1 for the 70%, 85%, and 100% ET irrigation levels, respectively. No significant differences existed in alfalfa yield with respect to horizontal perpendicular distance from the dripline with the exception of the 0.76 m distance, which yielded less in the drier and warmer year 2006. Large and significant decreases in alfalfa yield and crop water productivity occurred with successive harvests, with the first harvest having 272% and 196% of the fifth harvest yield and crop water productivity, respectively. Plant-available soil water decreased as the season progressed for all irrigation levels, but to a much greater extent for the 70% ET level, averaging at the time of the fifth seasonal harvest only 41% and 54% of the soil water for the 85% and 100% ET irrigation levels, respectively. These large seasonal decreases in soil water for the 70% ET irrigation level would be anticipated to be of even greater concern in extended multiple-year drought periods. This fact coupled with the 102 mm reduction in seasonal irrigation amount for the 85% ET irrigation level compared to the 100% ET irrigation level leads to a recommendation of scheduling replacement of 85% of the ET minus precipitation when subsurface drip irrigating alfalfa in the Central Great Plains. This study was conducted in a region with deep silt loam soils where approximately 60% of the average annual precipitation occurs during the summer months. Additionally, 125 mm of fall irrigation was applied during the dormant fall season to reduce root intrusion and rodent damage. These combined facts need to be considered when applying the results of this study to other regions and when using different irrigation management strategies.

Sunflower, Soybean, and Grain Sorghum Crop Production as Affected by Dripline Depth

A 5-year field study (2004-2008) using irrigation water from an unlined surface reservoir was conducted to examine the effect of dripline depth (0.2, 0.3, 0.4, 0.5, or 0.6 m) on subsurface drip-irrigated rotational crop production of sunflower, soybean, and grain sorghum on a deep silt loam soil in western Kansas. Additional years (1999-2003) of data were included in the analysis of long-term dripline flowrates as affected by dripline depth. Crop seed germination and plant establishment with the subsurface drip irrigation system was not examined in this field study. There were no significant differences in crop yields or yield components in any year of the study with the exception of the number of soybean pods/plant in 2007. In that year, the number of pods/plant was significantly greater for the deeper dripline depths, but this improvement was not reflected in significantly greater soybean yield due to compensation from the other yield components. Measured crop water use and calculated water productivity (yield/water use) also were not significantly affected by dripline depth for any crop in any year. Crop water use varied less than 4% and water productivity varied less than 8% with dripline depth from the mean values for a given crop within a given year, but water productivity tended to be greater for the intermediate 0.4 m dripline depth. There was a tendency for the deeper dripline depths to have greater amounts of plant available soil water and this tendency was stronger as the crop season progressed and for deeper portions of the crop root zone. However, there were neither significant differences in plant available soil water in the upper (0 to 0.9 m) and lower root zones (0.9 to 2.4 m) at physiological maturity of the crop in any year, nor in the total 2.4 m soil profile. The lack of significant differences in crop yields, water use, water productivity and plant available soil water at physiological maturity suggests that dripline depths ranging from 0.2 to 0.6 m are acceptable for crop production of these three crops on the silt loam soils of the region. Measurements of plot dripline flowrates during the period 1999 through 2008 indicated a tendency for deeper driplines to have reduced flowrates and these flowrate reductions were statistically significant in 2001, 2006, 2007, and 2008. Although the reason for these plot flowrate reductions cannot be fully ascertained, it seems likely they were caused by emitter clogging related to an interaction between dripline depth and irrigation water quality for which the rationale was not determined.

Water use efficiency of irrigated cotton in Uzbekistan under drip and furrow irrigation

The main goal of this research was to measure cotton water use, and to determine irrigation water scheduling parameters associated with optimal seed-lint yield and irrigation water use efficiency, which are poorly understood in the Central Asian Republic of Uzbekistan. A cotton ( Gossypium hirsutum L.) field experiment with drip irrigation in comparison to furrow (conventional) irrigation was conducted on a deep silt loam soil (Calcic Xerosol) at the Central Experiment Station of the Uzbekistan National Cotton Growing Research Institute at Tashkent in 2003, 2004 and 2005. To investigate irrigation scheduling, the field capacity ( F C) index was adopted, which was 0.30 m 3 m −3 in this soil. Irrigations were scheduled when soil water in the root zone was depleted to specific fractions of F C, e.g., 70% of F C, for each of three main plant growth periods (germination–squaring; squaring–flowering; beginning of maturation–maturation). Crop water use, which we here define as the sum of transpiration and evaporation, was established using the soil water balance approach on a weekly basis. Soil profile water content was determined using a neutron moisture meter (NMM), which was calibrated in polyvinyl chloride (PVC) access tubes for each differing soil layer. Under drip irrigation and the optimal mode (70–70–60% of F C) of irrigation scheduling, 18–42% of the irrigation water was saved in comparison with furrow irrigated cotton grown under the same condition; and irrigation water use efficiency increased by 35–103% compared with that of furrow irrigation. Seed-lint cotton yield was increased 10–19% relative to that for furrow irrigated cotton. The irrigation scheduling rule developed here should be considered an improved practice for drip irrigated cotton that is applicable to irrigated Calcic Xerosols of Uzbekistan.

DRIPLINE DEPTH EFFECTS ON CORN PRODUCTION WHEN CROP ESTABLISHMENT IS NONLIMITING

A four-year yield study (1999-2002) was conducted to examine the effect of dripline depth on subsurfacedrip-irrigated field corn grown on the deep silt loam soils of western Kansas. An additional year (2003) was included in theanalysis of long-term dripline flow rates and temperatures at the soil/water interface along the dripline. Germination of thefield corn with the subsurface drip irrigation system was not examined in this field study. Results indicate that dripline depthsranging from 0.20 to 0.61 m are acceptable for field-corn production on silt loam soils in the region. Averaged over the 4 yearsof the study, yields were slightly less for the deepest (0.61 m) dripline depth and water use was slightly less for the 0.51- and0.61-m depth compared to the 0.20-, 0.30-, and 0.41-m depths. There were no apparent effects of dripline depth on long-termflow rates. The results suggest that other factors external to the study might have a larger influence on selection of driplineinstallation depth. These other factors might include producer preferences, tillage schemes, rodent management, perceivedneed for surface wetting for germination, and installation draft requirements and costs.

DEVELOPMENT OF A BEST MANAGEMENT PRACTICE FOR NITROGEN FERTIGATION OF CORN USING SDI

A four-year study was conducted in western Kansas on a deep, well-drained, loessial Keith silt loam (Aridic Argiustoll; fine silty, mixed, mesic) to develop a Best Management Practice (BMP) for nitrogen (N) fertigation for corn using subsurface drip irrigation (SDI). Residual ammonium- and nitrate-N levels in the soil profile, corn yields, apparent nitrogen uptake (ANU), and water use efficiency (WUE) were utilized as criteria for evaluating six different N fertigation rates, 0, 90, 135, 180, 225, and 275 kg/ha. A BMP was developed indicating an N fertigation level of 180 kg/ha with the total applied N including other N-sources of approximately 215 kg/ha. The BMP also states that irrigation is to be scheduled and limited to replace approximately 75% of crop evapotranspiration (ETc). Corn yield, ANU, and WUE all plateaued at the same level of total applied N that corresponded to the 180-kg/ha N fertigation rate. Average yield for the 180-kg/ha N fertigation rate was 13.4 Mg/ha. Corn yield to ANU ratio for the 180-kg/ha N fertigation rate was high (53:1). Results emphasize that high-yielding corn production also can be efficient in nutrient and water use. The BMP can be used for managing SDI fertigation of corn on the deep silt loam soils of western Kansas.

Subsurface drip irrigation for corn production: a review of 10�years of research in Kansas

Kansas State University initiated studies in 1989 to develop the methodology for successful application of subsurface drip irrigation (SDI) for corn production on the deep silt loam soils of the Central Great Plains, USA. Irrigation water use for corn can be reduced by 35–55% when using SDI compared with more traditional forms of irrigation in the region. Irrigation frequency has not been a critical issue when SDI is used for corn production on the deep silt loam soils of the region. A dripline spacing of 1.5 m has been found to be most economical for corn grown in 0.76 m spaced rows. Nitrogen fertigation was a very effective management tool with SDI, helping to maximize corn grain yield, while obtaining high efficiencies of nitrogen and water use. The research SDI systems have been utilized since 1989 without replacement or major degradation. SDI systems lasting 10–20 years are cost competitive for corn production with the more traditional forms of irrigation in the Great Plains for certain field sizes.

Jack pine establishment in Ontario: 5-year comparison of stock types ± bracke scarification, mounding, and chemical site preparation

Field experimentation was begun in 1984 to assess performance of jack pine (Pinus banksiana Lamb.) (2 + 0 bareroot and FH408 Japanese paperpot) in relation to mechanical site preparation, including Bracke scarification with and without supplementary mounding, and site preparation using Roundup® herbicide. Twenty treatments encompassed 4480 trees in 40-tree plots split equally between bareroot and paperpot stock. The study site, about 200 km north of Sault Ste. Marie, Ontario, had deep silt loam soil. After 3 growing seasons, survival was significantly higher among bareroot than among paperpot stock, but survival no longer differed significantly (P < 0.05) between stock types 2 years later. In years 4 and 5, the rate of increase in mean total height of bareroot stock was 11% less than that of paperpot stock, though bareroot stock was 40 and 4.7 cm greater in mean total 5th-year height and 5th-year height increment, respectively. Paperpot stock needed mechanical site preparation more than did bareroot stock. By the end of year 5, positive responses of survival and growth to mounding had become clear in both stock types; however, although mound size had little or no effect on survival or total height, mean stem volume was significantly (P < 0.01) greater on 20-L vs. 10-L mounds. Fifth-year mean stem volume was also significantly (P < 0.01) greater on mineral-on-organic (M/O) than on mineral-on-mineral (M/M) mounds. Chemical site preparation had no effect on relative growth rates beyond year 3. Indices that combined survival with total height or stem volume after 5 years show the significant (P < 0.01) superiority of: 20-L vs. 10-L mounds, M/O vs. M/M mounds, and chemical vs. no-chemical site preparation.

Fertilization Fails to Increase Diameter Growth of Sawlog-size Northern Hardwoods in Upper Michigan

Five hundred individual, sawlog-size crop trees in a selectively managed northern hardwood stand were fertilized with 2.61 kg (5.75 lbs) of N-P-K fertilizer per tree in June 1970. The stand is predominantly sugar maple (Acer saccharum Marsh.) growing on a deep silt loam soil of good site quality. Three- and six-year diameter at breast height (dbh) and basal area growth were analyzed by treatment and diameter class. Fertilization did not increase dbh or basal area growth during either measurement period. Mean annual dbh growth of both fertilized and control trees was 0.41 cm (0.16 in.); trees in all diameter classes grew at essentially the same rate. Nearly half of the study trees grew 2.54 cm (1.0 in.) or more during the 6-year period, and fertilization did not change this proportion. Natural supplies of nutrients in good hardwood soils appear adequate for rapid growth of these species. Periodic cuttings maintain superior growth rates and contributes to efficient nutrient cycling. Fertilization is not recommended on sites like this because growth responses are not likely to justify costs.