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Chilean Journal of Agricultural Research
Instituto de Investigaciones Agropecuarias, INIA
ISSN: 0718-5820
EISSN: 0718-5839
Vol. 75, No. 1, 2015, pp. 98-104
Bioline Code: cj15014
Full paper language: English
Document type: Research Article
Document available free of charge

Chilean Journal of Agricultural Research, Vol. 75, No. 1, 2015, pp. 98-104

 en Relationship between mineralized nitrogen during anaerobic incubations and residual effect of nitrogen fertilization in two rice paddy soils in Chile
Villaseñor, Diego; Zagal, Erick; Stolpe, Neal & Hirzel, Juan

Abstract

An important N source for rice ( Oryza sativa check for this species in other resources L.) is mineralization of the organic forms of N present in the soil. The correct N determination will help to optimize the amount of fertilizer used. Our objective was to calculate an index that relates crop N uptake from previous N fertilization and N mineralized in rice paddy soils. To do so, we used two rice paddy soils, Alfisol and Vertisol, in Chile under different anaerobic incubation times and temperatures. We determined both soil mineralization and residual effect of fertilization in the previous season under field and laboratory conditions in an Alfisol and a Vertisol managed with a rice monocrop. Anaerobic incubations were carried out at 20 and 40 ºC; and at five different times (0, 7, 14, 21, and 28 d). Our results indicate that residual fertilization affects N mineralization, which increases in both paddy soils when compared with the control without N. In the Alfisol it fluctuates between 6.1 and 13.3 mg N-NH4+ kg-1, whereas in the Vertisol ranged between 18.4 and 28.0 mg N-NH4+ kg-1. Crop N uptake as a residual effect of applied N ranged between 29.3 and 33.9 kg N ha-1 in the Alfisol and 28.3 and 45.8 kg N ha-1 in the Vertisol. Thus, N mineralization is mainly affected by incubation time, temperature, and N fertilization rate of the previous crop season; it can be represented by quadratic models with high determination values, R2 = 0.73** and R2 = 0.78**, for Alfisol and Vertisol, respectively. Moreover, we found that the best incubation time and temperature were 7 d at 20 °C and 21 d at 40 °C, for the Altisol and Vertisol, respectively. In addition, there are potential savings in the next rice crop season from 0.86 to 0.43 kg N applied for each 1 mg N kg-1 mineralized in the Alfisol and Vertisol, respectively. We conclude that crop N uptake was related to mineralized N and that the equation here developed that relates them is a good predictor to optimize fertilizer use in rice paddy fields.

Keywords
Residual effect; fertilization nitrogen; Oryza sativa

 
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