PERDAS DE FÓSFORO POR LIXIVIAÇÃO EM NEOSSOLO REGOLÍTICO ADUBADO COM ESTERCO BOVINO CURTIDO EM CONDIÇOES SEMIÁRIDAS

O fósforo (P) é considerado um nutriente imóvel no solo, pois o P liga-se fortemente ao Fe e Al. No entanto, foi observado em solos arenosos que o Fe e Al, mesmo em pequenas quantidades, influenciam a lixiviação de P. Objetivou-se avaliar a perda de P em amostras de um Neossolo Regolítico adubado e não adubado com esterco bovino curtido, e relacionar as perdas de P com as formas de Fe e Al. Foram coletadas quatro amostras de solo adubado e não adubado com esterco bovino curtido na profundidade de 0 - 10 cm no município de Esperança – PB. Após a coleta foram feitas análises de fertilidade do solo, incluindo P em Mehlich – 1 e P em água, Fe e Al extraído com Oxalato de amônio e Ditionito – citrato e bicarbonato. O ensaio de lixiviação foi realizado através do método de deslocamento miscível utilizando colunas acrílicas preenchidas com solo e uma solução salina de KCl e CaCl2 a 0,001M para a lixiviação. A área A2 teve o maior teor de Pw (14,45 mg kg -1) e Pext (54,50 mg kg -1), esta mesma área apresentou a maior perda de Plix (128,83 mg L-1). A correlação entre Plix e as formas de Fe e Al foram não significativas. O Plix teve maior correlação com as formas mais cristalinas de Fe e Al. A maior perda de P foi observada até 20 NVp. Palavras – chave: Deslocamento miscível de P; Sorção e Lixiviação de P   PHOSPHORUS LOSSES BY LEACHING IN NEOSSOLO REGOLÍTICO FERTILIZED WITH CURED CATTLE DUNG IN SEMI-ARID CONDITIONS   ABSTRACT: Phosphorus (P) is considered an immobile nutrient in the soil, since P is strongly bound to Fe and Al. It was observed in sandy soils that Fe and Al, even in small amounts, influence the leaching of P. The objective was to evaluate P loss in samples of a Regolithic Neossol fertilized and not fertilized with tanned manure, and to relate P losses with the Fe and Al forms. Four samples of soil fertilized and not fertilized with tanned manure at depth of 0 - 10 cm in the municipality of Esperança - PB. After collection, soil fertility analyzes were performed, including P in Mehlich - 1 and P in water, Fe and Al extracted with ammonium oxalate and Dithionite - citrate and bicarbonate. The leaching assay was performed by the miscible displacement method using soil-filled acrylic columns and a 0.001M KCl and CaCl2 saline solution for the leaching. The area A2 had the highest content of Pw (14.45 mg kg -1) and Pext (54.50 mg kg -1), this same area presented the highest loss of Plix (128.83 mg L-1). The correlation between Plix and the Fe and Al forms were not significant. Plix had a higher correlation with the more crystalline forms of Fe and Al. The greatest loss of P was observed up to 20 NVp. Keywords: Miscible displacement of P; P Sorption and Leaching

Arbuscular mycorrhizal fungal community assembly in the Brazilian tropical seasonal dry forest

Abstract Introduction Here, we compare the arbuscular mycorrhizal fungal (AMF) community composition in soils from the root zone of the exotic invasive species Prosopis juliflora (EXO soils) and soils from the root zone of the native species Mimosa tenuiflora (NAT soils) from five locations in the Brazilian tropical seasonal dry forest, Para\uedba, Brazil, using morphological analyses. Results AMF community composition in EXO and NAT soils were dissimilar. Available phosphorus, diversity index, spore abundance, and species richness were the main factors differing between the EXO and NAT soils. In general, the most dominant order present in the soils were Glomerales (44.8%) and Gigasporales (41.4%). The most abundant AMF genus in all studied soils was Funneliformis . Conclusions Differences in AMF community composition were associated with (1) differences in the dominant plant species ( P. juliflora vs. M. tenuiflora ) and (2) changes in soil chemical factors (soil, pH, total organic carbon, total nitrogen, and available P) in EXO soils. These results contribute to a deeper view of the AMF communities in exotic soils and open new perspectives for ecological processes involving AMF species and exotic plant species in the Brazilian tropical seasonal dry forest

Arbuscular mycorrhizal fungi in Mimosa tenuiflora (Willd.) Poir from Brazilian semi-arid

Abstract Many plant species from Brazilian semi-arid present arbuscular mycorrhizal fungi (AMF) in their rhizosphere. These microorganisms play a key role in the establishment, growth, survival of plants and protection against drought, pathogenic fungi and nematodes. This study presents a quantitative analysis of the AMF species associated with Mimosa tenuiflora, an important native plant of the Caatinga flora. AMF diversity, spore abundance and root colonization were estimated in seven sampling locations in the Ceará and Paraíba States, during September of 2012. There were significant differences in soil properties, spore abundance, percentage of root colonization, and AMF diversity among sites. Altogether, 18 AMF species were identified, and spores of the genera Acaulospora, Claroideoglomus, Dentiscutata, Entrophospora, Funneliformis, Gigaspora, Glomus, Racocetra, Rhizoglomus and Scutellospora were observed. AMF species diversity and their spore abundance found in M. tenuiflora rhizosphere shown that this native plant species is an important host plant to AMF communities from Brazilian semi-arid region. We concluded that: (a) during the dry period and in semi-arid conditions, there is a high spore production in M. tenuiflora root zone; and (b) soil properties, as soil pH and available phosphorous, affect AMF species diversity, thus constituting key factors for the similarity/dissimilarity of AMF communities in the M. tenuiflora root zone among sites

Could biological invasion by Cryptostegia madagascariensis alter the composition of the arbuscular mycorrhizal fungal community in semi-arid Brazil?

Biological invasions pose a serious threat to native semi-arid areas of Brazil, especially in areas of the state of Ceará that are typically invaded byCryptostegia madagascariensis, an exotic plant species from Madagascar. However, how this biological invasion influences the composition of the arbuscular mycorrhizal fungal (AMF) community and how this affects further invasion by C. madagascariensis is not well known. Here we tested how inoculation with species of AMF affects the development of this invasive plant. We analyzed and compared the AMF community composition of four different stages of biological invasion by C. madagascariensis, and examined the effects of inoculation with these four AMF communities, plus a dominant AMF species (Rhizoglomus intraradices) on plant dry biomass, root colonization, plant phosphorous concentration, and plant responsiveness to mycorrhizas of plants of C. madagascariensis. We found that all studied treatments (except the inoculum from the native plant root zone) promoted the growth of C. madagascariensis and lead to a higher P concentration. Our results demonstrate that the invader might be altering the composition of the AMF community in field conditions, because inoculation with this community enhanced invader growth, root colonization, and P uptake

Decomposition Rate of Organic Residues and Soil Organisms’ Abundance in a Subtropical Pyrus pyrifolia Field

The use of mulching, compost, and their interaction on organic residue (OR) decomposition rate (k), time of residue decay, primming effect, and soil organisms’ community composition was tested in a 16-year P. pyrifolia field experiment conducted from January 2020 to June 2021. A 2 2 factorial design was used with compost and mulching as the two factors within four blocks. OR decomposition was characterized by using litter bags with different mesh, and soil organisms were identified at family level. The half-decay rate (hd), total-decay rate (td), and remaining residue mass (Rm) varied among the organic residue management and mesh-type. The highest values of k and primming effect were found in litter bags with 15 mm2 size containing compost in the plots that received compost. For soil organisms’ abundance and richness, the highest values were found on plot that received both mulching and compost. The observed results suggested that the OR management determined organic matter decomposition, soil organisms’ abundance and richness in an Acrisols of the Southern Brazil. Soil organisms were the main factors contributing to the data variance (e.g., Acaridae, Blattidae, Chrysopidae, Halictophagidae, and Forficulidae)

Litter Deposition and Nutrient Cycling of Invaded Environments by Cryptostegia madagascariensis at Tropical Cambisols from Northeastern Brazil

Cryptostegia madagascariensis is an invasive plant species that covers 11% of the Brazilian northeastern territory, but its role on the litter trait in tropical ecosystems remains unclear. Here, we analyzed and compared the litter deposition, litter nutrient content, soil organic matter, and the litter decay rate from invaded and non-invaded environments by C. madagascariensis at a tropical Cambisol. The PCA analysis revealed that litter deposition, litter quality, and soil organic matter were correlated with the invaded environment. We grew plant species in greenhouse conditions to obtain a standard litter material to use in our litter bags in field conditions. We found that litter decay rate was higher in the invaded environment than in the non-invaded one. Our results suggest that C. madagascariensis changes litter traits in tropical ecosystems that in turn create negative plant–soil feedback to the native species by creating a physical barrier on soil surface and to promote its own rhizosphere

Forest–Fruticulture Conversion Alters Soil Traits and Soil Organic Matter Compartments

Fruticulture in the Amazonian Rainforest is one of the main causes of deforestation, biodiversity loss, and soil erosion. Fruticulture plays a key role in the soil traits and soil organic matter (SOM) compartments by altering the soil ecosystem. Our aim was to assess the influence of Forest–Fruticulture conversion on soil traits, and SOM fractions in Brazil’s Legal Amazon. The experiment was carried out in field conditions using four land uses as main treatments: Bixa orellana, Theobroma grandiflorum, Paullinia cupana, and the Amazon Rainforest. The soil physicochemical traits were analyzed using samples that were collected from 0–5, 5–10, and 10–20 cm soil depth by using grids (10 × 10 m) with 36 sampling points. Our results showed that the Fruticulture promoted an increase in bulk density, GMD, aggregate diameter, soil porosity, gravimetric moisture, sand, clay, carbon associated with humic acid, and, the sum of bases (K+, Ca2+, and Mg2+), while the Amazon Rainforest showed the highest values of silt, soil P content, SOC, p-SOC, m-SOC, carbon associated with fulvic acid, humine, and soil C stock. Overall, the fruticulture farming systems have negative effects on SOM compartments. The results of our study highlight the importance of considering fruticulture with endemic plant species by promoting soil fertility and soil aggregation