Cm Of Irrigation Research Articles

Soybean Response to Water: A QTL Analysis of Drought Tolerance

Soybean [Glycine max (L.) Merr.] yield, when regressed on water needed to replenish 0 to 100% seasonal evapotranspiration (ET), generates an estimate of season‐specific water‐use efficiency (WUE). The impact of unpredictable water deficits might be lessened if high‐yielding genotypes had a smaller beta. Our objective was to determine the genetic basis of beta and carbon isotope discrimination (CID), a theorized indicator of transpiration efficiency (TE). A ‘Minsoy’ × ‘Noir 1’ population of 236 recombinant inbred lines (RILs), genotyped at 665 loci, was evaluated in six water treatments (100, 80, 60, 40, 20, and 0% ET) for 2 yr. Water stress was mild in 1994, but high temperatures and no rainfall in 1995 led to a drought so severe that the 100% ET treatment required 41 cm of irrigation. The 1995 yield‐to‐water regression was highly linear (28 kg ha−1 cm−1). Genotype × water (G × W) interaction was due to genotypic heterogeneity in beta The CID vs. beta correlation was low (r = 0.26), so selection for better leaf TE may not improve crop WUE. Selection of low beta (less sensitivity to drought) will be difficult, given the yield beta vs. yield correlation (r = 0.71). The major quantitative trait loci (QTL) for yield beta, yield, and CID were coincident with maturity and/or determinancy QTLs, except for a CID QTL in linkage group U09‐C2, but it had no effect on beta Genetic improvement of soybean yield performance under drought would be better achieved by coupling a high‐yield grand mean with a high‐ (not low‐) yield beta

Field Study: Influence of Fly Ash on Leachate Composition in an Excessively Drained Soil

Alternatives to landfilling fly ash may be to use it as a soil amendment since it is fine textured and could alter soil texture and thus improve water retention. However, fly ash contains elevated B, soluble salts, and trace element concentrations that could adversely affect plant and soil quality. Objectives were to characterize leaching of soluble salts, plant nutrients, and trace elements in a sandy soil amended with a high rate of fly ash (∼662 Mg ha−1). We established field plots in an Evesboro loamy sand using typical agricultural equipment. Lysimeters were installed to a depth of 120 cm and used to collect leachate over a 9 mo period. We also used microplots (1.0 by 1.0 m) and similar ash rates to characterize leaching under controlled conditions. Lysimeters were installed at four depths in each microplot (15, 30, 60, and 120 cm) and water applied with a rainfall simulator. Boron and soluble salts were leached from the rooting zone after ∼38 cm of natural rainfall or 42 cm of irrigation. Calcium and S were the dominant plant macronutrients in leachates while Cu, Mn, and Zn were the only detectable micronutrients. Peak concentrations of these elements were detected after ∼50 cm of rainfall or irrigation and decreased to below or near initial concentrations by the conclusion of the study. Nickel was the only detectable trace element in leachates, however, concentrations were variable and <0.15 mg L−1. Results suggest that if fly ash incorporation is properly timed to allow for natural leaching, adverse effects will be minimal.

Timing of limited irrigation and N-injection for grain sorghum

When subsurface irrigation sources are lacking in humid and subhumid regions, high yearly precipitation may allow for storage of surface water in farm ponds and lakes for irrigation. Irrigation at selected growth stages may avoid critical stress for crops with some drought tolerance, such as grain sorghum [Sorghum bicolor (L.) Moench]. Because grain sorghum is responsive to N, injecting fertilizer N through the irrigation system also may improve production. The objective of this study was to determine the effect of timing of limited-amount irrigation and N fertigation on grain sorghum yield; yield components; grain N content; and N uptake at the 9-leaf, boot, and soft dough stages. The experiment was conducted from 1984 to 1986 on a Parsons silt loam (fine, mixed, thermic, Mollic Albaqualf). The experiment was designed as a 6 × 2 factorial plus two reference treatments. Six timings for irrigation were targeted at the 9-leaf (9L), boot (B), soft dough (SD), 9L-B, 9L-SD, and B-SD growth stages. N application systems were either 112 kg N ha−1 surface-banded preplant or 56 kg N ha-1 preplant and 56 kg N ha−1 injected through the irrigation at a rate of 28 kg N ha−1 per 2.5 cm of irrigation. Two reference treatments included were one receiving N but no irrigation and one receiving neither N nor irrigation. In 1984, irrigation generally increased grain sorghum yield by nearly 1 Mg ha−1. However, yield was not affected by selection of irrigation timing, N application method, or the interaction of the two factors. This was partly because early irrigations increased kernels/head, whereas later irrigations increased kernel weight. Above average rainfall during the growing season, especially just prior to the 9-leaf, boot, and soft dough growth stages, resulted in no irrigations in 1985. In 1986, yield was increased by early (9-leaf) irrigations as compared to soft dough irrigations. Early irrigations resulted in higher kernels/head; however, rainfall after the soft dough irrigation may have masked any treatment effect on kernel weight. As in 1984, N application method did not affect grain sorghum yields, even though yield was reduced to less than 3 Mg ha−1 with no N nor irrigation. In both 1984 and 1986, N uptake at succeeding growth stages appeared to respond to irrigations made at previous growth stages. Injecting half of the fertilizer N through the irrigation system did not affect N uptake compared to applying all N preplant. The lack of response to fertigation may be related to the low leaching potential of the soil used in this study.

Influence of Soil Moisture on Phytotoxicity of Cinmethylin to Various Crops

Field trials were conducted in 1986 and 1987 to determine the effects of moisture on cinmethylin activity. The herbicide was applied preemergence at rates of 0.0, 0.3, 0.6, and 0.9 kg ai ha−1to both dry and moist sandy loam soil, followed by varying irrigation regimes. Plant species used in the study included soybean, snap bean, cotton, peanut, and cucumber. Peanut was the most tolerant to cinmethylin, followed by cotton, soybean, snap bean, and cucumber. When cinmethylin was applied to a moist soil, less crop injury resulted than when it was applied to a dry soil. If 7.6 cm of water was applied shortly after cinmethylin application to a dry soil, severe crop injury occurred. When 2.5 cm of irrigation was applied within 8 h or at 5 days after cinmethylin application to a dry soil, crop injury was reduced when compared to applying 7.6 cm irrigation.

Influence of Simulated Rainfall and Soil Moisture on Herbicidal Activity of Cinmethylin

Field trials were conducted in 1986 and 1987 to determine the effects of moisture on herbicidal activity of cinmethylin applied preemergence at 0.0, 0.3, 0.6, and 0.9 kg ai ha to both dry and moist sandy loam soil. Herbicide application was followed by varying amounts of irrigation. Weed species included velvetleaf, prickly sida, green foxtail, and barnyardgrass. When cinmethylin was applied to a moist soil or when 2.5 cm of irrigation was applied 5 days after cinmethylin application to a dry soil, overall weed control was reduced. Optimum weed control resulted from cinmethylin application to dry soil followed either by a 2.5-cm irrigation within 8 h or a 7.6-cm irrigation within 36 h.

Control of Black Vine Weevil Larvae (BVW) with Soil Insecticides in Connecticut, 1984

Abstract Two methods of application were used to test the efficacy of soil insecticides in 2 growing media common to local nurseries. The tests were carried out on a Merrimac fine, sandy loam field at the Valley Laboratory (pH 5.4) and a 1:1:1 peat, composted hardwood bark, and sand “shrub mix” (pH 5.6) in 2-gaI plastic containers. The 2 test media were planted to Taxus in 1982. Both areas were maintained using standard cultural practices with the containers being kept under overhead irrigation. From 6 Jun, when the insecticides were applied, through 6 Aug container grown plants received 1-2 h of water per day while the sandy loam plots which were not irrigated received a total of 13.5 cm of rain occurring on 14 different days. In the “shrub mix” test each treatment was a single container and in the sandy loam each treatment was a single container, and in the sandy loam each treatment consisted of 4 plants in a 0.6-m by 1.35-m plot. Both tests were randomized and replicated 4 times. Insecticides were applied 2 ways: spread over the soil surface or incorporated into the upper 2 cm of soil by hand cultivation. Liquids were poured into containers in 100 ml of water and to field plots in 312 ml (400 gal/acre), with a small watering can. Granules were mixed with 230 g of sand and were applied with a shaker bottle to each field plot, and in the container test the granules were spread undiluted on the soil. Both tests areas received 1.5 cm of irrigation 1 h after treatment. Approximately 400 ml of soil was collected on 7 Jun and 6 Aug from each container and field plot and immediately placed in plastic bags and frozen.

Field Measurements of Ammonia Loss from Surface Applications of Urea Solution to Bare Soil1

AbstractFactors influencing ammonia (NH3) volatilization from surface‐applied urea have been studied extensively; however, almost all research has been done in a manner that modifies the environment compared to field conditions. Results from such studies, therefore, may incorrectly assess actual losses in the field. Our objective was to evaluate the magnitude of NH3volatilization and how soil temperature, soil water, and other environmental factors affected rates of loss. Three studies were conducted to assess the volatilization of NH3from surface‐applied urea, two on a silt loam and one on a very fine sandy loam soil. A mass‐balance micrometeorological method, which produces very minimal disturbance of the natural environment was used in all studies. Diurnal patterns of NH3loss, which coincided with the fluctuations in surface temperature and water content, were found in each study. In all studies, loss followed most closely the pattern of urea hydrolysis. Urea hydrolysis in the surface soil was slowed by dry conditions and approached zero when the soil was near “air dryness.” Rainfall of 0.86 cm did not prevent further NH3loss from Muir silt loam soil (fine‐silty, mixed, mesic Pachic Haplustolls). Three simulated rainfalls with 0.5 cm of irrigation separated by 3 and 4 days did not curtail loss from Haynie very fine sandy loam soil (coarse‐silty, mixed, mesic Typic Udifluvents), but rather enhanced the rate of volatilization, probably due in part to an increased rate of urea hydrolysis.

EFFECT OF WATER GRADIENT ON SORGHUM GROWTH, WATER RELATIONS AND YIELD

A field study was conducted during the 1980 growing season to determine the effects of soil moisture gradient on sorghum water relationships, growth, and yield of four hybrids: Sorghum bicolor L. ’G-623 GBR,’ ’RS 626,’ ’RS 671’ and ’A 28+’. June to September was warmer than normal (2.3–4.8 °C), with precipitation of only 16.2 cm during the cropping season. Sprinklers provided a continuously decreasing moisture gradient away from the water source. Plant height, dry matter, and leaf area index (LAI) decreased as watering level decreased. Higher leaf diffusive resistance and lower water potentials were associated with decreasing plant height and decreasing LAI. Canopy temperature (Tc) of the water-stressed sorghum was generally 3.2–3.7 °C warmer than canopy temperatures of well-watered plants. Canopy temperature also correlated well with water use by all hybrids. The average canopy minus air temperature [Formula: see text] was positive for all hybrids receiving less than 25 cm of irrigation and precipitation during the growing season, which corresponds to soil moisture values of 0.32 maximum available. Increasing the watering levels increased the water use efficiency (WUE) for total dry matter and grain yield.

LEACHING LOSSES OF TWO NUTRIENTS AND AN HERBICIDE FROM TWO SANDY SOILS DURING TRANSIENT DRAINAGE

Concentrations of K, NO3-N, and Terbacil were measured in subsurface drainage from shallow-tilled (ST) and deep-tilled (DTL) plots of an acid, sandy Spodosol during a 2-week period of transient water flow after 7.6 cm of irrigation. Generally, the concentrations of all these solutes were higher in ST drainage water than in DTL drainage. An exception occurred during the initial water discharge from the subsurface drains, when the NO3-N concentrations were considerably greater in water flowing from DTL soil. Nitrification of fertilizer NH4-N in the heavily limed DTL soil was assumed to contribute to the initially higher NO3-N concentrations in the drainage. Measurements of volumetric drainage from the drains and soil solution within the soil region influenced by the drains clearly confirmed previous observations that the rates of water discharge from the ST drain were much greater than those from the DTL drain. The cumulative drainage from ST soil over the 2-week period was approximately twice that from DTL. In ST soil the water table rose to within 100 cm from the surface during the infiltration of water applied by pop-up sprinklers, but in DTL soil the water table rose to within 60 cm from the soil surface. The slower drainage, the higher soil-water contents, and the higher contents of clay minerals and organic matter in the upper 60 cm of the DTL soil resulted in K, NO3-N, and Terbacil discharges that were only 30, 37, and 14% as large as those for ST soil. Thus, the deep-tilled, acid, sandy soil discharged less drainage water, K, NO3-N, and Terbacil during the 2-week period than occurred from the shallow-tilled soil. Leaching losses of K and NO3-N included contributions of residual nutrients from previous fertilizer applications and were considered large for the short duration of this study.