9 research outputs found
Future prospects for large farms located in lorraine on clayed soils and limestone compounds (rendosols)
From a concrete case located in a small natural area of Lorraine (Haye),
the interest of an agro-eco-pedological study was highlighted. After observations
of the ground (pedological charts on various scales), physical-chemical and
isotopic analyses and output analysis determined by GPS, it became possible :
1) to simulate the potentialities of a farm or of a piece of land located in this area, 2) to determine the importance of compartmentalized heterogeneity on the
outputs in order to modulate the use of fertilizers, 3) to outline the socioeconomic
consequences according to the foreseeable climate evolutions.A partir d'un cas concret et localisé dans une petite
région naturelle de Lorraine (Haye), il a été mis en
évidence l'intérêt d'une étude
agro-écopédologique. A la suite d'observations de terrain (cartes
pédologiques à différentes échelles), d'analyses
physico-chimiques et isotopiques et de la détermination des rendements par
GPS, il devient possible: 1) de simuler les potentialités d'une
exploitation ou d'une parcelle située dans cette région, 2) de
déterminer l'importance de
l'hétérogénéité parcellaire sur les
rendements et donc de moduler les fertilisants, 3) d'esquisser les
conséquences socio-économiques sur les exploitations en fonction
des évolutions climatiques prévisibles
Influence of the soil climate on the evolution of the nitrogenous compounds in the soils of Lorraine and their consequences on the water quality
In order to establish the influence of the soil climate on the transfer
mechanisms of the element N, under naturally constituted forms or industrial
syntheses, in soil, water, plant systems, we put in place in the fields two
procedures. The first concerned the cultivated sites of the four main types of soil
found in Lorraine. The annual lixiviation of nitrates beyond the Ap level can be
large and go beyond 100kg / ha of N.NO3
-. It varies according to the soils, the
year and the season and we observe that the nitrates are mainly lixiviated in
autumn. The values obtained in-situ, compared to those of the potential
mineralization in controlled conditions, show the importance of the interaction
between climactic parameters and biophysical chemical properties of the soils
intervening on the mineralization of the endogenous nitrogen stocks thus the risks
of lixiviation notably between crops. Then on a light chalk/clay soil, the burying
of a carbon substrate (hop) in end of season, allowed a limitation to the annual
lixiviation of the nitrates of about 25%.
The use of a fertilizer marked under controlled conditions, allowed us to
see the formation of different sections of the internal cycle of the nitrogen and the
bio availability of this fertilizer for a spring crop while allowing for the risks of
enrichment in nitrate ions in the underlying waters. This study allowed us to
establish the participation of the fertilizer in the possible risks of a pollution of
nitrates to a level of 21%; also to underline the importance of the duration of the
microbic biochemical immobilizations of fertilizers given to these four types of
soils; finally, we observe a variety of the kinetic of remineralization from the
newly-formed different organic azotes.Afin de préciser l'influence du pédoclimat sur
les mécanismes de transfert de l'élément azote (sous
formes de composés naturels ou de composés issus de
synthèses industrielles) dans les systèmes sols, eaux, plantes,
nous avons mis en place plusieurs protocoles. Dans le premier les horizons
cultivés des quatre principaux types de sols lorrains ont
été pris en considération et soumis aux mêmes
contraintes climatiques. La lixiviation des nitrates au-delà de l'horizon
Ap est importante et peut dépasser annuellement 100 kg/ha de
N.NO-3. Elle varie selon les sols, l'année et la
saison et nous constatons que les nitrates sont majoritairement lixiviés en
automne. Les valeurs obtenues in situ, comparées à celles du
potentiel de minéralisation en conditions contrôlées,
montrent toute l'importance de l'interaction entre les paramètres
climatiques et les propriétés bio-physico-chimiques des sols sur
l'expression de la minéralisation des réserves azotées
endogènes, donc de leur potentiel de lixiviation. Un second protocole a
permis de mettre en évidence une limitation de la lixiviation des nitrates
d'environ 25 % suite à l'enfouissement automnal d'un substrat
carboné (paille d'orge). L'utilisation d'un engrais marqué, nous a
permis d'observer l'évolution des différents compartiments du
cycle interne de l'azote et de leur biodisponibilité pour une
céréale de printemps tout en prévoyant les risques
d'enrichissement en ions nitrate des eaux sous jacentes. Cette étude a
permis de préciser la participation de l'engrais à la pollution
nitrique à hauteur de 21% et de souligner toute l'importance de
l'immobilisation microbienne des engrais par le sol. Enfin, sous conditions
contrôlées, nous montrons les variations de l'immobilisation des
engrais apportés et surtout de leur cinétique de
reminéralisation en fonction du pédoclimat
Influence de l'apport de composés organiques sur l'adsorption et la désorption des ions phosphates en sol ferrallitique
International audienc
Transformations of nitrogen fertilizers in brazilian amazonia soils
We have compared the effect of15N urea and15N ammonium sulfate on the process of stabilization in organic matter and mineralization in three soils of central Amazonia, classified as Oxisol, Ultisol, and low-humic gley. During the first month of incubation in the laboratory, the nitrogen fertilizer amendment slightly increased mineralization of organic nitrogen in both acid soils (Oxisol and Ultisol). In these soils, 60% of the nitrogen added was recovered as NH4* after 2 months incubation, while in the low- humic gley soil, 50% of the applied nitrogen was nitrified. The incorporation of15N fertilizer in the organic matter of the latter soil was higher (30%) than in the acid soils. Incorporation in the acid soils, though low, was more important for N derived from urea than ammonium sulfate. For the Oxisol, nitrogen incorporation in organic matter values varied between 12% and 19%, and 7-9% for the Ultisol. © 1995 Taylor & Francis Group, LLC
Efficiency of nitrogen-15-labelled fertilizers for rice and rye-grass cultivated in an Ultisol of Brazilian Amazonia
The objective of this study was to determine the efficiency of two N fertilizers, (NH4)2SO4 and urea, for rice (Oryza sativa L.) and rye-grass (Lolium multiflorum L.) cultivated in an Ultisol of central Amazonia using 15N as a tracer. Rice was cultivated in the field, while rye-grass was grown in a phytotron. Fertilization with (NH4)2SO4 caused a 16% increase in the yield of rice grains and urea a 36% increase. In both crops total N uptake and N use efficiency of the fertilizers were higher for urea than for (NH4)2SO4. The low values for N derived from fertilizer showed that the fertilizers contributed little to the total N absorbed by the plants. The 'priming effect' or positive added N interaction (ANI) between the fertilizer N and soil organic N was observed, especially with urea. Immobilization by soil microorganisms was greater in the presence of urea, while losses were always higher with the (NH4)2SO4 treatments. These losses were significant, and their reduction should allow more efficient use of this N fertilizer. It is possible that the N use efficiency was higher for urea due to a pH increase, caused by urea hydrolysis, which in turn may have favoured the activity of nitrifying bacteria in this extremely acid soil