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Agronomy Journal Abstract - Soil Fertility & Crop Nutrition

Phosphorus and Potassium Fertilizer Effects on Alfalfa and Soil in a Non-Limited Soil


This article in AJ

  1. Vol. 105 No. 6, p. 1613-1618
    unlockOPEN ACCESS
    Received: Jan 31, 2013
    Published: September 6, 2013

    * Corresponding author(s): filippo.rimi@unipd.it
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  1. Stefano Macolinoa,
  2. Leonard M. Lauriaultb,
  3. Filippo Rimi *a and
  4. Umberto Ziliottoa
  1. a Dep. of Agronomy Food Natural resources Animals and Environment, Univ. of Padova, viale dell’Università 16, AGRIPOLIS 35020, Legnaro, Padova, Italy
    b Dep. of Plant and Environmental Sciences, New Mexico State Univ., Tucumcari, NM 88401


Fertilization strategies for high-yielding alfalfa (Medicago sativa L.) should take in account the increase in soil nutritional status that occurred during the last decades in areas with intensive agricultural use. A field study was conducted at the University of Padova, northeastern Italy, to determine the response of alfalfa yield and nutritive value to various combinations of P and K rates in a soil lacking nutrient deficiency. Alfalfa cultivar Delta was seeded in March 2005 on a silt loam soil having 38 mg kg–1 available P and 178 mg kg–1 exchangeable K. Nine treatments deriving from the combination of three P fertilization rates (0, 100, and 200 kg ha–1 P2O5) and three K rates (0, 300, and 600 kg ha–1 K2O) were compared in a randomized complete block design. Plots were harvested at bud stage during three growing seasons (2005–2007) and dry matter (DM) yield, forage nutritive value, P and K contents, canopy height, and stem density were measured at each harvest. Soil samples were collected at the end of the research period for determination of available P and exchangeable K. The results demonstrated that P application had no impact on yield and did not interact with K in determining productivity, while K had a positive effect on yield. However, the 300 kg ha–1 K2O rate appeared sufficient to maximize yield, without adverse effects on the forage nutritive value. Data from soil analyses showed that alfalfa has a high K uptake even when it is fertilized at high rates.

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