Predicting Need for Phosphorus Fertilizer by Soil Testing During Seeding of Cool Season Grasses
| Autor: | Stephanie C. Hamel, Joseph R. Heckman |
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| Rok vydání: | 2006 |
| Předmět: | |
| Zdroj: | HortScience. 41:1690-1697 |
| ISSN: | 2327-9834 0018-5345 |
| Popis: | Recent changes in soil testing methodology, the important role of P fertilization in early establishment and soil coverage, and new restrictions on P applications to turf suggest a need for soil test calibration research on Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb), and perennial ryegrass (Lolium perenne L.). Greenhouse and field studies were conducted for 42 days to examine the relationship between soil test P levels and P needs for rapid grass establishment using 23 NJ soils with a Mehlich-3 extractable P ranging from 6 to 1238 mgkg -1 . Soil tests (Mehlich-1, Mehlich- 3, and Bray-1) for extractable P were performed by inductively coupled plasma-atomic emission spectroscopy (ICP). Mehlich-3 extractable P and Al were measured to evaluate the ratio of P to Al as a predictor of need for P fertilizer. Kentucky bluegrass establishment was more sensitive to low soil P availability than tall fescue or perennial ryegrass. Soil test extractants Mehlich-1, Bray-1, or Mehlich-3 were each effective predictors of need for P fertilization. The ratio of P to Al (Mehlich-3 P/Al %) was a better predictor of tall fescue and perennial ryegrass establishment response to P fertilization than soil test P alone. The Mehlich-1, Bray-1, and Mehlich-3 soil test P critical levels for clipping yield response were in the range of 170 to 280 mgkg -1 , depending on the soil test extractant, for tall fescue and perennial ryegrass. The Mehlich-3 P/Al (%) critical level was 42% for tall fescue and 33% for perennial ryegrass. Soil test critical levels, based on estimates from clipping yield data, could not be determined for Kentucky bluegrass using the soils in this study. Soil testing for P has the potential to aid in protection of water quality by helping to identify sites where P fertilization can accelerate grass establish- ment and thereby prevent soil erosion, and by identifying sites that do not need P fertilization, thereby preventing further P enrichment of soil and runoff. Because different grass species have varying critical P levels for establishment, both soil test P and the species should be incorporated into the decision-making process regarding P fertilization. Grass seedlings often respond positively to P fertilization because seed P reserves are easily exhausted because rapidly growing and dividing cells use P. Seedling root systems have limited contact with P in the soil, and diffusion, the dominant mechanism by which P is supplied to plant roots from the soil solution, is an especially slow process when the soil P concentration is low (Barber, 1995). Thus, P fertilizer is often routinely applied at the time of seeding cool season grasses in an effort to hasten establishment. Indiscriminate use of P fertilizers, without regard to soil test P level, has come under increased scrutiny. Excessive P accumulation in soils and its associated problems with runoff and water quality deterioration are of increasing concern (Correll, 1998; Sharpley et al., 1994; Sims, 1998). In an attempt to limit P nutrient runoff, some municipalities are regulating P fertilizer application to turf (Rosen and Horgan, 2005; The Citizen of Morris County, 1992). However, rapid soil coverage by an increasingly dense sod is crucial to the prevention of surface nutrient runoff and erosion. Therefore, the use of P fertilizer may sometimes be justified, even on high P soils, if it hastens grass establishment. Based on soil samples received from the public in 2004 by the Rutgers Soil Testing Laboratory (analyzed using Mehlich-3 soil test), 24% of samples had soil test P ratings in the below optimum range ( 69 mgkg -1 ). These soil test P ratings are for general crops and are not specific for grass establishment and the diversity of soils onto which grasses are seeded. To make sound recommendations, it is imperative to know where P fertilization is necessary and where it is inappropriate. Furthermore, the ability of P |
| Databáze: | OpenAIRE |
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