Changes in the stocks of C and N in organic matter fractions in soil cropped with coffee and fertilized with sunn hemp and ammonium sulfate / Alterações dos estoques de C e N nas frações da matéria orgânica de solo cultivado com cafeeiro e adubado com crotalária e sulfato de amônio
Pereira, Wander Douglas; Martins Neto, Fábio Lúcio; Santos, Ricardo Henrique Silva; Oliveira, Teógenes Senna de; Caballero, Segundo Sacramento Urquiaga.
Semina Ci. agr.
; 39(3): 999-1014, maio-jun. 2018. tab, graf
Artículo
en Inglés
| VETINDEX | ID: vti-18615
Despite the potential to provide N to crops, the rapid incorporation of green manure nutrients into stable fractions of organic matter in the soil (SOM) may reduce the efficiency of green manuring. Thus, the objective of this work was to characterize the changes of C and N stocks in fractions of SOM cultivated with coffee (Coffea arabica L.) and fertilized with sunn hemp (Crotalaria juncea) and ammonium sulfate. To study the changes in organic C (OC) and total N (TN) in soil and fractions of SOM over time, soil samples were collected in the 05 and 510 cm layers, with the initial sampling done prior to the application of sunn hemp residues and ammonium sulfate. Five samples were collected every 2 months after the application of the legume and ammonium sulfate. The soil samples were submitted to densimetric and granulometric fractionation, obtaining the free light organic matter (F-LOM), particulate organic matter (POM), and organic matter associated with minerals (MAM). OC and TN stocks were then determined in soil and the SOM fractions. The changes in the stocks of OC (ΔStcC) in the soil in relation to time zero were positive in the evaluations carried out in the two layers. The fractions of SOM showed positive ΔStcC at almost all of the evaluated times. The N supplied to the soil in the form of mineral and organic fertilizer promoted an increase of 0.24 Mg ha-¹ of N in the 05 cm layer until after 60 days. Of this total, 0.03 Mg ha-¹ was associated with F-LOM, 0.07 Mg ha-¹ with POM, and the remainder was associated with MAM. Nearly 60% of the N that was supplied to the soil was drawn to the stable fractions of the SOM, indicating a rapid stabilization of this nutrient in the most recalcitrant organic compartments. Despite that, the variations in N stocks of MAM became smaller over time, and eventually became negative, in relation to time zero.[...](AU)
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BR68.1
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