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A need for a grower acceptable irrigation scheduling technique was brought about by rapid expansion in irrigated land in the Southeast. A modified Jensen‐Haise evapotranspiration formula was adapted by Lambert et al. into an irrigation scheduling and forecasting model for this region. The purpose of this study was to determine if the Lambert model was as effective as tensiometer scheduling in meeting irrigation needs of field corn (Zea maysL.). Corn was grown in seven replicated field experiments and two nonreplicated production scale experiments. Yield and water were compared after irrigation was applied either when soil water pressure in the 150 to 300 mm zone fell below −30 kPa as indicated by tensiometers or when called for by the model. The comparisons were conducted for 3 years on two soils, Tifton loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudult) and Bonifay sand (loamy, siliceous, thermic, grossarenic Plinthic Paleudult). In five of the comparisons a nonirrigated check was included. The treatment irrigated by the Lambert model yielded 11.1 Mg ha−1over all seven experiments; the tensiometer irrigated treatment yielded 11.0 Mg ha−1, and the nonirrigated treatment yielded 4.3 Mg ha−1. There were no significant differences between the two irrigated treatments within any year on either soil. The mean yearly water required by the model was 285 mm, compared to 237 mm for the tensiometer. In four of the seven experiments the model called for more water than the tensiometer treatment. Model predicted soil water content was generally greater than measured soil water content for the Bonifay soil but was not significantly different for the Tifton soil. Experience with the Lambert model indicated that it was difficult to determine some of the required model inputs but with correct inputs the model could accurately predict soil water content and corn water requirements.

Four field sites which have been irrigated with various levels of secondary treated sewage effluent for 9 to 11 years have been examined for phosphorus content in soil water extracted with suction lysimeters. The cornfield site on Hublersburg clay loam irrigated with effluent had an average P concentration of 0.329, 0.070, and 0.046 mg/liter in soil water at 15, 60, and 120 cm respectively compared to 0.043, 0.046, and 0.037 mg/liter, respectively, under an adjacent fertilized, but unirrigated control. Year round application of effluent including 2 years of effluent plus sludge to reed canarygrass (Phalaris arundinaceaL.) on Hublersburg clay loam resulted in average soil water concentrations of 0.170, 0.100, and 0.052 mg P/liter at 15, 60, and 120 cm, respectively. In an abandoned field on Hublersburg clay loam where no P was removed by crops, P concentrations were 0.140, 0.103, and 0.076 mg P/liter for the treated plot and 0.038, 0.047, and 0.042 mg P/liter for the control at 15, 60, and 120 cm, respectively. Only the 15‐cm depth had significantly higher P concentrations in the treated plot. A hardwood forest located on a Morrison sandy loam soil was irrigated year round. Phosphorus concentrations in soil water were 0.349, 0.080, and 0.087 mg/liter for the treated vs. 0.059, 0.039, and 0.039 for the control at 15, 60, and 120 cm, respectively. Leaching losses were calculated from concentration of P in soil water at 120 cm and from leaching volume which was rainfall plus irrigation minus potential evapotranspiration. Over all years of treatment no site had leaching losses of > 3% of the total applied.

Municipal sewage effluent with sludge injected and effluent alone were spray‐irrigated on reed canarygrass (Phalaris arundinaceaL.) and corn (Zea maysL.), respectively. In the maximum level (10 cm/week) reed canarygrass treatment, application rates for Cu, Zn, Cd, and Pb were 15.5, 25.5, 0.162, and 9.1 kg/ha in 1972 and 7.7, 13.2, 0.135, and 7.8 kg/ha in 1973. Rates of application for Cu, Zn, Cd, and Pb in the maximum level (7.5 cm/week) cornfield treatment were 0.6, 2.0, 0.029, and 1.1 kg/ha in 1972 and 0.6, 2.4, 0.032, and 2.4 kg/ha in 1973. Reed canarygrass was irrigated year‐round, while corn was irrigated only during the growing season. Copper and Zn concentrations and total uptake in the treated reed canarygrass area were generally higher than in the control for all cuttings of 1972 and 1973. Total uptake of heavy metals in the corn area control was usually as high or higher than in the treated areas. Copper and Zn concentrations and uptake in the effluent irrigated corn area were lower than in the treated reed canarygrass area. Data show a relative exclusion of Cd by Zn in the plant material, since Cd/Zn ratios in the harvested crops are lower than in either the applied waste water or the 0.1NHCl extractable fraction of the treated soils. Accumulation of applied heavy metals in the treated soils was > 93% of the amounts applied in 1972 and 1973 for all heavy metals in the reed canarygrass area and slightly less in the corn area.

Two waste water‐treated sites at The Pennsylvania State University Wastewater Renovation Project were monitored to measure nitrate and total N in soil water. Both long‐term waste water irrigation and varied irrigation rates were examined. Soil water was sampled by porous cup samplers. The concentration of N at the 120‐cm depth was taken as a measure of N which escaped the root zone and which would leach to the ground water. Recharge volume was calculated from irrigation, rainfall, and potential evapotranspiration. A hardwood forest site located on a well‐drained sandy loam soil was irrigated year round with secondary municipal effluent at a rate of 5 cm/week. In the last 6 of 9 years of effluent treatment 83% of the 4,954 kg N/ha added leached from the site. Nitrate concentration in soil water at the 120‐cm depth was generally > 15 mg N/liter. The hardwood forest was also ineffective in keeping nitrate concentration below 10 mg N/liter at the 120‐cm depth when the 5‐cm weekly application was split into two 2.5‐cm irrigations or when it was lowered to 2.5 cm/week year round. An abandoned old field site planted with white spruce (Picea glaucaMoench) and located on a well‐drained clay loam soil was irrigated with effluent at 5 cm/week from Apr. through Nov. each year, beginning in 1963. Nitrate concentration at the 120‐cm depth rarely exceeded 10 mg N/liter and only 36% of the 1,246 kg N/ha applied leached during the 6th through the 9th years of this effluent treatment. In the 10th and 11th years, when the application rate was increased to 7.5 cm/week, nitrate concentration exceeded 10 mg N/liter at the 120‐cm depth, and the amount of N which leached increased to 75% of the amount applied.

Forage yields of ‘Coastal’ bermudagrass [Cynodon dactylon(L.) Pers.] drop sharply in late summer and fall, even though warm temperatures continue. The objective of this study was to examine relationships among meteorological parameters and forage yield of irrigated and rain‐fed Coastal bermudagrass fertilized annually with 672 kg ha−‐1of N plus adequate P and K. Irrigation maintained soil water pressure above –25 kPa, as indicated by gypsum blocks. Forage from six irrigated and six rain‐fed plots was harvested at eight 24 d intervals. Three‐year average yields for the eight growth periods ranged from 295 kg ha−1in October to 2907 kg ha−1in June. Stepwise multiple regression of yields from individual cuttings with various meteorological parameters indicated that daylength was the single most important variable related to yield (r2=0.64). Total rainfall plus irrigation, mean minimum temperature, growing degree days, and mean daily solar radiation could be associated with yield to a limited extent. Over years, yield was most highly correlated with daylength and solar radiation, (r=0.95 and 0.93, respectively,) indicating that these factors were largely responsible for low yields of Coastal bermudagrass forage in the fall. The small correlation between average yields and average temperatures (r=0.46) or average growing degree days (r=0.37) for the eight 24‐d growth periods resulted from the failure of Coastal bermudagrass to grow well in the fall even when water, fertilizer, and temperature were adequate.

Maintaining efficient N nutrition for irrigated corn (Zea mays L.) grown on deep sands is difficult due to low N supplying capabilities and leaching losses of applied N. Scheduled applications of N by the use of center‐pivot irrigation equipped with modern solution injection equipment should reduce leaching and increase N‐use efficiency. The objective of this study was to compare the efficiency of scheduled applications of N through sprinkler irrigation with the more conventional side‐dress method for maintaining N nutrition and obtaining high yields. Field experiments were conducted for 5 years on a Bonifay sand (loamy, siliceous, thermic, grossarenic, Plinthic Paleudult) using solid‐set irrigation systems. Treatments included side‐dressing, sprinkler application for 10 to 11 weeks after planting according to anticipated N needs, and combinations of the two methods, as well as, differential N rates ranging from 168 to 350 kg ha‐1. Maximum yields were obtained with approximately 280 kg N ha‐1. Scheduled sprinkler application of N did not provide better N nutrition than conventional side‐dressing. In 4 of the 5 years of the study, corn was planted in soil which had near average rainfall during the winter and some leaching rain in the early growing season. In those years, side‐dressing was equal or superior to sprinkler application; while a combination of side‐dressing young corn followed by later sprinkler applications produced the highest yields. These responses may be the result of the timing of N applications or of an improved N uptake from the banded method (side‐dressing) in comparison to a broadcast method (sprinkler application).

A field study was conducted on two waste water‐treated sites to evaluate the effectiveness of various cutting treatments for controlling nitrogen (N) leaching. Secondary municipal sewage effluent was applied at 7.5 cm/week during the growing season to Kentucky bluegrass (Poa praetensisL.), which received treatments of no cutting, biweekly mowing, and triannual hay harvest. Effluent was also applied at rates of 0, 5.0, and 10.0 cm/week to indigenous vegetation in an abandoned field which received treatments of no cutting, once, and twice‐annual harvests. Soil‐water was sampled with porous‐cup samplers. The N concentration in the 120‐ to 150‐cm depth was taken as a measure of N which escaped the root zone and which would leach to the ground water. Recharge volume was calculated from irrigation, rainfall, and potential evapotranspiration. Soil‐water from the 150‐cm depth in the Kentucky bluegrass consistently contained < 10 mg/liter of mineral N. Mineral N concentration of soil‐water did not differ significantly among the cutting managements. Even though no vegetation was removed from the no‐cutting and the mowed plots, they were as effective as the harvested plots in controlling N leaching past the 150‐cm depth in the 2‐year study. For the oldfield vegetation, there was no significant difference in mineral N concentration in soil‐water at the 120‐cm depth between the 5.0‐ and 10.0‐cm/week irrigation rates. The mineral N concentration at 120 cm under both irrigation rates was affected by time of year and by cutting treatments. The twice‐annual harvest controlled N leaching more effectively than not cutting. The once‐annual harvest was more effective than not cutting for the 10‐cm/week rate but not for the 5.0‐cm/week rate. During the late summer and fall mineral N in the leachate increased to > 10 mg N/liter for the no cutting but not for the harvested oldfields. For reliable control of N leaching, removal of the N in harvested biomass was recommended.