15N uptake fom manure and fertilizer sources by three consecutive crops under controlled conditions

Revista Brasileira de Ciência do Solo

Héctor Mario Quiroga Garza²  Jorge A. Delgado¹  José Antonio Cueto Wong¹  William C. Lindemann¹ 

[1] ,Instituto Nacional de Investigaciones Forestales, Agrícolas y PecuariasCoahuila,México

关键词: denitrification;    nitrogen use efficiency;    annual ryegrass;    salinity;    sudangrass;    denitrificação;    eficiência de uso do nitrogênio;    raygrass anual;    salinidade;    sudangrass;   

DOI  :  10.1590/S0100-06832009000500018

来源: SciELO

【 摘 要 】

There are several regions of the world where soil N analysis and/or N budgets are not used to determine how much N to apply, resulting in higher than needed N inputs, especially when manure is used. One such region is the North Central "La Comarca Lagunera", one of the most important dairy production areas of Mexico. We conducted a unique controlled greenhouse study using 15N fertilizer and 15N isotopic-labeled manure that was labeled under local conditions to monitor N cycling and recovery under higher N inputs. The manure-N treatment was applied only once and was incorporated in the soil before planting the first forage crop at an equivalent rate of 30, 60 and 120 Mg ha-1 dry manure. The 15N treatments were equivalent to 120 and 240 kg ha-1 (NH4)2SO4-N for each crop. The total N fertilizer for each N fertilized treatment were 360, and 720 kg ha-1 N. We found very low N recoveries: about 9 % from the manure N inputs, lower than the 22 to 25 % from the fertilizer N inputs. The manure N recovered belowground in soil and roots ranged from 82 to 88 %. The low recoveries of N by the aboveground and low soil inorganic nitrate (NO3-N) and ammonium (NH4-N) content after the third harvested suggested that most of the 15N recovered belowground was in the soil organic form. The losses from manure N inputs ranged from 3 to 11 %, lower than the 34 to 39 % lost from fertilizer N sources. Our study shows that excessive applications of manure or fertilizer N that are traditionally used in this region will not increase the rate of N uptake by aboveground compartment but will increase the potential for N losses to the environment.

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