An in situ incubation technique to measure the contribution of organic nitrogen to potatoes

Field experiments which consisted of the incubation of soil within polyvinylchloride (PVC) tubes inserted in glass jars previously buried in potato crop rows were conducted in order to measure the contribution of soil organic matter and organic amendments to the N nutrition of the crop. The experiments were carried out in Braganca, NE Portugal, in the summer seasons of 1996-1998. Five treatments including farmyard manure, poultry manure, municipal solid wastes, urea and the control were used. Manures and urea were applied in rates which correspond to 100 kg N/ha. Nitrogen released from soil organic matter and manures was checked through crop N recovered and petiole nitrate concentrations. In the plots of urea treatments 80.1, 68.4 and 98.8 mg NO 3 -N kg -1 were released during the entire growing seasons of 1996, 1997 and 1998, respectively. In the control treatments 64.1, 41.5 and 55.4 mg NO 3 -N kg -1 were recorded. The mean values of NO 3 -N yielded from amended plots were not statistically different than control, excluding the plots of poultry manure on the initial sampling dates at the start of incubation. The measured amounts of inorganic N mineralized in the field from native soil organic matter were five to eight times higher than previous laboratory estimates from soil analysis. These results demonstrated that soils with low levels of organic matter could release significant amounts of inorganic N during a cropping season. Soil N availability estimated from the incubation technique was confirmed by petiole nitrate concentrations and closely related to the crop N recovered. However, in the plots of urea treatments some inconsistencies were found, probably originating from the leaching of urea as a molecular form to layers below the limit of soil coring. Soil N balance showed that more than 82% of inorganic N released from organic matter came from the 14-cm soil surface layer.

[1]  M. Adams,et al.  Nutrient cycling and nitrogen mineralization in eucalypt forests of south-eastern Australia , 1986, Plant and Soil.

[2]  S. Recous,et al.  The fate of labelled15N urea and ammonium nitrate applied to a winter wheat crop , 1988, Plant and Soil.

[3]  T. Yasuda,et al.  Immobilization, mineralization and the availability of the fertilizer nitrogen during the decomposition of the organic matters applied to the soil , 1979, Plant and Soil.

[4]  S. Jarvis,et al.  Comparison of methodologies for field measurement of net nitrogen mineralisation in arable soils , 1999, Plant and Soil.

[5]  R. H. Fox,et al.  Field evaluation of several chemical indexes of soil nitrogen availability , 1990, Plant and Soil.

[6]  A. Gupta,et al.  Evaluation of leaf analysis as a guide to nitrogen and phosphorus fertilization of potato (Solanum tuberosum L.) , 1976, Plant and Soil.

[7]  F. Pomares,et al.  Indexes of assessing N availability in sewage sludges , 2004, Plant and Soil.

[8]  J. W. Groenigen,et al.  Relationships Between Soil Nitrogen Availability Indices, Yield, and Nitrogen Accumulation of Wheat , 2002 .

[9]  S. Subler,et al.  Comparison of buried bag and PVC core methods for in situ measurement of nitrogen mineralization rates in an agricultural soil , 1995 .

[10]  S. K. Schmidt,et al.  Nitrogen Mineralization and Microbial Biomass Nitrogen Dynamics in Three Alpine Tundra Communities , 1995 .

[11]  I. Burke,et al.  Evaluation of Methods for Estimating Net Nitrogen Mineralization in a Semiarid Grassland , 1995 .

[12]  S. W. Wang,et al.  Denitrification, Immobilization, and Mineralization in Nitrate Limited and Nonlimited Residue-Amended Soil , 1995 .

[13]  M. A. Rodrigues.  Influência da fertilização mineral e orgânica na cultura da batata. Eficiência de utilização do azoto , 1995 .

[14]  F. Vinther.  Nitrogen fluxes in a cropped sandy and a loamy soil measured by sequential coring , 1994 .

[15]  K. Killham,et al.  Investigation of N mineralization-immobilization dynamics in blanket peat to optimize the N economy of improved grass pasture , 1994 .

[16]  T. Engels,et al.  Effect of the rate of N fertilizer on apparent net mineralization of N during and after cultivation of cereal and sugar beet crops , 1993 .

[17]  M. Mazzarino,et al.  Nitrogen Mineralization and Soil Fertility in the Dry Chaco Ecosystem (Argentina) , 1991 .

[18]  A. Wild,et al.  Russell's Soil Conditions and Plant Growth , 1988 .

[19]  R. J. Raison,et al.  Methodology for studying fluxes of soil mineral-N in situ , 1987 .

[20]  K. Mengel.  Dynamics and Availability of Major Nutrients in Soils , 1985 .

[21]  J. Castellanos,et al.  Mineralization of Manure Nitrogen—Correlation with Laboratory Indexes , 1981 .

[22]  D. Westermann,et al.  Measuring Soil Nitrogen Mineralization Under Field Conditions , 1980 .

[23]  P. F. Pratt,et al.  Value of Manure and Sewage Sludge as N Fertilizer1 , 1978 .

[24]  R. H. Fox,et al.  Field Testing of Several Nitrogen Availability Indexes 1 , 1978 .

[25]  L. Overrein,et al.  Factors Affecting Urea Hydrolysis and Ammonia Volatilization in Soil1 , 1967 .

[26]  J. M. Bremner,et al.  Comparison and Evaluation of Laboratory Methods of Obtaining an Index of Soil Nitrogen Availability1 , 1966 .

[27]  C. F. Eno,et al.  Nitrate Production in the Field by Incubating the Soil in Polyethylene Bags , 1960 .

[28]  D. A. V. Schreven,et al.  Mineralization of Organic Nitrogen in Soil , 1955 .