Flood-irrigated Fields Research Articles

Effect of drying period and soil moisture on egg hatch of the tadpole shrimp (Notostraca: Triopsidae).

Tadpole shrimp (Triops spp.) are potential biological control agents against larval mosquitoes in temporary ponds and flood-irrigated fields. In some rice field situations, however, they may become pests that uproot and eat young rice plants. In cursory observations, it has been reported that tadpole shrimp eggs do not readily hatch on flooding when the soil or substrate containing eggs is moist before flooding. The relationship between drying (moisture content) of soil and tadpole shrimp hatch was determined in studies conducted in mesocosms at the University of California Aquatic and Vector Control Research facilities at Riverside and at Oasis in the Coachella Valley of southern California. In laboratory hatching trials, an increase in hatch of Triops longicaudatus (LeConte) with declining soil moisture content was demonstrated (t = 8.4, P less than 0.001; r2 = 0.76). In field trials in mesocosms at Riverside, egg hatch increased with increased drying period and declining soil moisture content (G = 29.8, P less than 0.01). No hatch of eggs occurred after 3 d of drying, when soil moisture content was high, but a high level of hatching occurred after 7 and 14 d of drying, when soil moisture declined to low levels. At Oasis, soil moisture did not decrease with drying time because of porous soil and capillary action of water from adjacent flooded mesocosms and thick vegetation covering the pond bottoms. Therefore, hatch rates at Oasis were not associated with the length of the drying period (G = 35, P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of Irrigation Flows through Irrigation Turnouts

Accurate measurement of applied water volumes in surface irrigation fields is important towards improving irrigation efficiencies and management of the surface irrigation system. In flood irrigated fields, applied water may be supplied through spiles, or turnout pipes connecting the field directly to the supply canal. A simple measurement of head loss across the turnout pipe is all that is necessary to estimate onflow rates when the total head loss coefficient for the spile is known. The total head loss coefficient is primarily dependent on the entrance and exit head losses, and entrance head losses depend on the orientation of flow in the canal relative to the spile. For spile flows perpendicular to the axis of canal flow, the entrance head loss is greater than traditionally assumed. This paper reports results of field calibration of spiles having a supporting bracket for the cover plate, perpendicular flow and into which flow develops a sizable vortex that dissipates energy. A calibration curve relating head loss to spile discharge is developed from the field data.

Sugarbeet Insect Pests Control, 1989

Abstract Granular insecticide treatments were applied at planting time to 2 separate flood-irrigated fields located in Carbon County in eastern Mont. Each field was planted on 'Monohy 149' on 20 Apr. The fields were 3-yr stands of alfalfa. Granular insecticides were applied as a 5 inch band on top of the row through a ground-driven Gandy applicator and lightly incorporated with a drag chain. Treatments were replicated 3 times in a randomized complete block. Individual replicates were 6 rows (22-inch row spacing) × 100 ft. Stand counts were made by counting the number of plants in 3 ft of row in 10 locations in each replicate. Feeding damage by PFB was assessed by removing 30 seedling plants from each replicate and rating each seedling as injured (presence of feeding scars) or uninjured. SBRM damage was determined for each treatment by removing 10 beets/replicate. Beets were rated using the following scale: 0, no damage; 1, 1-4 small scars of pinhead size; 2, 5-10 pinhead-size scars or 3 large scars; 3, more than 3 large scars; 4, 4 large scars to one-quarter of the root surface covered with scars; 5, one-quarter to one-half root surface covered with scars; 6, one-half to threequarters root area blackened by scars; 7, more than three-quarters root surface blackened.

Spatial and Temporal Variability of Water Content and Infiltration on a Flood Irrigated Field

ABSTRACT The variability of water contents and cumulative infiltration was measured on a flood irrigated field over four irrigations. Changes in water storage at 44 locations were calculated from the differences between the water contents measured before and after each irrigation with a neutron probe. Infiltration was measured with 42 single-ring infiltrometers located on a single transect down the field. The variability in calculated water storage was very consistent from irrigation to irrigation, with specific locations consistently measuring either high or low. Rankings of the locations from low to high water storage showed little variation between irrigations. Variograms showed that water storage was spatially correlated to distances of 30 m and that the spatial structure was identical from irrigation to irrigation. Changes in water storage due to irrigation were more variable but still displayed a consistency over time. The variogram for the change in water storage had a large nugget value and ranges near 20 and 90 m. Infiltration equation parameters measured with the infiltrometers were extremely variable over time as indicated by low correlation coefficients. Depths of cumulative infiltration, however, were much more consistent over time with extreme values being consistently measured at the same locations. The spatial correlation of the cumulative infiltration depths extended to distances less than 3.8 m. Calculations of the irrigation uniformity from the infiltrometer measurements were less than uniformities based on measured water contents. The discrepancies between these two measures are due, in part, to difficulties in measuring infiltration parameters with ring infiltrometers that are representative of infiltration for the border as a whole and to the effects of lateral flow and redistribution on water content measurements.

Control of Sugarbeet Insect Pests, 1988

Abstract Granular insecticide treatments were applied at planting time to 2 separate flood-irrigated fields located in the Yellowstone Valley of eastern Montana. Field 1, previously in alfalfa, was planted to ‘Beta 3265’ on 24 May using an IH185 8-row planter. Granular insecticides were banded on top of the ridge through a ground-driven Gandy applicator and lightly incorporated with a drag chain. Each treatment and untreated control were replicated 10 times in a randomized complete block design. Individual replicates were 2 rows (22-inch spacing) by 2,500 ft. Field 2 was planted in ‘Beta 6566’ on 1 Apr using an Arts-Way Heath Airseeder. This field was a 3-yr stand of alfalfa. Insecticides were banded on top of the row through an electric-drive Gandy applicator and roto-incorporated 2-3 inches deep.

Effects of Pyrethroids and Miticides on Spider Mite, Southwestern Corn Borer and Predator Populations, 1982

Abstract This experiment was conducted in a late-planted, flood-irrigated corn field in northern Grant Co, KS. Ten treatments were arranged in a randomized complete block design with 4 replications. Each plot was 3 m wide (4 rows) and 15.2 m long surrounded by a 3-m wide border of untreated corn. The chemical treatments were made twice, on Jul 30 (corn at 16-leaf stage) and Aug 10 (corn at tassel stage). These treatments coincided with the oviposition period of the Southwestern Corn Borer (SWCB) according to the predictions of the KSU model for SWCB development. Treatments were applied with a high clearance sprayer with 20 gal of water/acre at 30 psi of CO2pressure. Spider mites and spider mite predators were sampled Jul 29, Aug 5 and Aug 24. Counts were made by searching the leaves on 1 side of 2 plants in each of the 2 center rows to give 4 half-plant samples per plot. The plants were selected at random on the first sampling date and flagged so that the same plant could be counted on each sampling date. While visually searching the plants, records were made of adult female spider mites, active stages of the predator mite and Oriusnymphs. Representative samples of spider mites were mounted for microscopic examination and all were determined to be the Banks grass mite. Five consecutive corn stalks were split in each plot and the number of stalks with live SWCB larvae were recorded. Corn yields were determined by hand harvesting corn from 20 row-ft of each of the 2 center rows in each plot. Yields were corrected to 15.5% moisture.

Miticide Efficacy Test, 1982

Abstract This experiment was conducted in a late-planted, flood-irrigated corn field in northern Grant Co, KS. Ten treatments were arranged in a randomized complete block design with 4 replications. Each plot was 3 m wide (4 rows) and 15.2 m long surrounded by a 3 m-wide border of untreated corn. The treatments were applied on 1 of 2 dates except for 1 treatment that received 2 applications. The early treatments were applied on Jul 30 when the corn was in the 16-leaf stage (pre-tassel) and the late treatments were applied on Aug 10 when the corn was in the tassel stage. The chemical treatments were made with a high clearance sprayer using a 3-m boom with 3 nozzles directed at each row (1 nozzle directly over the row and 2 suspended on 46 cm drop hoses). The equipment was calibrated to deliver 20 gal of water/acre at 30 psi of CO2pressure. Counts were made by searching the leaves on 1 side of 2 plants in each of the 2 center rows to give 4 half-plant samples per plot. Plants were selected at random on the first sampling date and flagged so that the same plant could be counted on each sampling date. A visual search was used to record adult female spider mites and active stages of predator mites. Representative samples of spider mites were mounted for microscopic examination and all were determined to be the Banks grass mite.