Nitrogen content in regosols under management in microphyllous and rosetophyllous desert shrubs

Abstract

The anthropogenic activities have been a factor in the degradation of natural resources, and therefore natural and mechanical techniques such as the roller aerator and fire have been implemented in order to reduce their impact. The content of total nitrogen content was assessed in a Regosol soil present in the Chihuahuan Desert, with microphyllous (MDS) and rosetophyllous desert shrubs (RDS), under treatment with roller aerator on three different dates: 2004 (RA-04), 2008 (RA-08) and 2011 (RA-11), as well as an area burnt in 2011 (BA-11) and a control area (C). Four composite samples of soil were collected at depths of 0-15 and 15.1-30 cm in each of 80 sites, and they were analyzed using the Kjeldahl method. The average contents of nitrogen in the MDS were: C= 0.174 %, RA-04= 0.087 %, RA-08= 0.080 %, RA-11= 0.261 % and BA-11= 0.195 %, whereas for the RDS they were C= 0.075 %, RA-04= 0.125 %, RA-08=0.082 %, RA-11= 0.170 % and BA-11= 0.178 %. Based on the variance analysis, there were differences (p≤0.05) by type of vegetation and treatment; no depth-related effects were observed. The values were rated low (MDS RA-08, 15.1-30 cm = 0.051%) to very high (MDS RA-11, 0-15 cm = 0.309 %). In both, the total nitrogen contents varied considerably after the mechanical treatments, as the tN increases or decreases according to the applied treatment and to the type of vegetation.