Irrigation Based on Soil Suction Measurements

The feasibility of tensiometer soil moistnre sensinK devices for schedolinK bermudagrass (Cynodon dactylon X C. transFaaknsis) torr irription and their impact on N fertilization practices under su~tropical conditions was assessed. Irription water savinp of 42 to 95% were obtained in sensor controUed plots over conventionaUy irripted plots. The Kfeatest benefit of the sensor system was achieved durinK periods of frequent but unpredictable rainfaU by eUminatinK unnecessary irriKations. Application of a wettinK aKent was necessary durinK extended dry periods to prevent localized dry spots when irription was limited by the sensor system to an as needed basis.Reduced irription by the sensor system resulted in better torr appearance and equal effectiveness of water-soluble and slow-release N sources.

mentioning

confidence: 99%

Moisture Sensor‐Controlled Irrigation for Maintaining Bermudagrass Turf¹

Augustin¹,

Snyder²

1984

“…In studies on many crops soil water potential has been found to be a major determiner of crop yield (Taylor and Ashcroft, 1972) despite the presence of uncontrolled meteorological factors that also influence plant water stress. Irrigation scheduling according to direct soil water potential measurements by tensiometer has been researched (Richards and Marsh, 1961) and practiced 745 for a number of crops, but available information is minimal for sunflower (Prunty, 1981 ).…”

mentioning

confidence: 99%

Soil Water and Population Influence on Hybrid Sunflower Yield and Uniformity of Stand¹

Prunty¹

1983

Sunflower (Helianthus annuus L.) hybrids do not respond identically to agronomic and environmental variables. The present study was conducted to quantify the influence of soil water potential and plant population on oilseed sunflower hybrids ‘Dahlgren 704’, ‘USDA 894’, and ‘Interstate 907’. Desire to refine knowledge of yield relationships was one motivation for the study, but a deeper stimulus was the need for basic knowledge of the detailed nature of sunflower stands. Hybrids were planted at four populations at two North Dakota sites in 1980. One site had Maddock (sandy, mixed Udorthentic Haploboroll) and Gardena (coarse‐silty, mixed pachic Udic Haploboroll) soils. This location received irrigation treatments limiting soil water potentials to minimums of ‐35, ‐70, and ‐105 J kg‐−1. The second site had Bearden (fine‐silty, frigid Aeric Calciaquoll) soil and was not irrigated. Yield increased with soil water potential from 201 g m−2 at – 105 J kg−11 to 284 g m−2 at ‐35 J kg−1. Dryland yields were 200, 179, and 164 g m−21 for hybrids 894,704, and 907. Population did not influence yields. However, irrigated and nonirrigated stand loss percentages increased with population at 0.8 and 2.2% per plant per square metre, respectively. Knowledge of the threshold population for stand loss provides a rationale for selection of population in the absence of yield differences because significant stand loss indicates a possibly undesirable level of intraspecific competition. Guidelines for irrigation scheduling for sunflower by use of tensiometers are now on a sounder experimental basis. Hybrids similar under irrigation yielded differently under dryland conditions.

“…In this study, sunflower response to soil water potential was evaluated by using the method of Richards and Marsh (10) to schedule irrigations and control the soil water potential at Oakes, North Dakota (1979). The comparison of yield estimation methods was also conducted at Oakes.…”

mentioning

confidence: 99%

Sunflower Cultivar Performance as Influenced by Soil Water and Plant Population¹

Prunty¹

1981

Information on the yield performance of sunflower (Helianthus annuus L.) as related to a range of soil water potential in the near‐optimum range has not previously been reported. Previous studies of sunflower plant population density effects on yield have lacked agreement. In this study three sunflower cultivars (‘Peredovic’, ‘894’, and ‘Northrup King 212’) were tested for response to soil water potential at Oakes, North Dakota and for response to population density at Carrington, North Dakota (irrigated) and Fargo, North Dakota (dryland). Yield was higher if the soil water potential in the root zone, as measured by commercial tensiometers, was limited to values of ‐20 cbar and ‐40 cbar and was lowered if the root zone water potential was allowed to drop to ‐75 cbar. There was no significant difference in seed yield between populations at thinning of 49,400, 59,300, and 69,200 plants/ha. A comparison of harvest methods at Oakes indicated that a number‐of‐heads harvest method increased yield estimates by 20% compared to an area harvest method. This comparison also showed that the harvest method used did make a significant difference in yield results obtained from the water potential experiment. It is hypothesized that harvest method may have influenced previous sunflower population density experiments similarly.