Study of two paddy field management practices: effects on soil carbon fractions and N-fixing capacity associated with Lotus spp

MAGUIRE VG; RODRIGUEZ AA; EZQUIAGA JP; GORTARI M; BOUILLY P; ROMERO FM; GÁRRIZ A; RUIZ OA

Congreso; XXXIII Argentinian meeting of plant physiology; 2021

The rice-pasture rotation is the main rice-cultivation system in Entre Ríos where Vertisol soils are the most suitable due to the presence of a Bt horizon with more than 45% of clay enabling the rice to stay flooded during the whole growing period. The management practices carried out in these ecosystems impact on the edaphic C and N levels and the C storage capacity. In order to account for this, soil C and N contents at two soil depths (0-10 cm and 10-30 cm) of two contrasting rice-production systems (RPR: rice-pasture rotation and RM: rice monoculture), were measured and compared to an undisturbed field (UDF) close to them. The RPR system showed the higher TOC, POC and TN levels and the lowest reductions percentages of the mentioned variables in relation to the UDF. The N-fixing capacity of the legume comprising the RPR system, L. corniculatus, was estimated by the 15N isotope abundance technique. In field conditions and when the average value of both reference plants was considered, the %Ndfa resulted to be 77.4 %. In addition, the presence of plant associated P solubilizing and N fixing microorganisms were evaluated. The results obtained show the importance, in terms of ecological and microbiological impact, of including pasture cycles along with rice cycles for achieving an ecologically and economically sustainable rice-production system