Phosphorus loss by surface runoff in no-till system under mineral and organic fertilization

Ernani

et al. 2016

Pesq. agropec. bras.

-The objective of this work was to assess the risk of phosphorus losses by runoff through an index based on the degree of P saturation (DPS), in cropland soils of Southern Brazil. Sixty-five highly representative cropland soils from the region were evaluated. Three labile P forms were measured (Mehlich-1, Mehlich-3, and ammonium oxalate), and four P sorption indexes were tested (phosphorus single sorption point and Fe+Al determined with the three extractors). Water-extractable P (WEP) was used as an index of P susceptibility to losses by surface runoff. The DPS was determined from the ratio between labile P and each sorption index. DPS values obtained from the ratio between Mehlich-1 P and the single P sorption point ranged from 1 to 25%, whereas those from Mehlich-1 P and Fe+Al (ammonium oxalate) ranged from 1 to 55%. All DPS types were highly correlated with WEP. From a practical stand point, the DPS obtained with both P and Fe+Al extracted with Mehlich-1 can be used to estimate the risk of P losses by runoff in soils of Southern Brazil.Index terms: eutrophication, runoff, single P sorption point, water quality. Limite do grau de saturação de fósforo para minimizar perdas de P por escorrimento superficial em solos agrícolas do Sul do BrasilResumo -O objetivo deste trabalho foi avaliar o risco de perdas de fósforo por escorrimento superficial por meio de um índice baseado no o grau de saturação de P (GSP) no solo, em solos agrícolas do Sul do Brasil. Foram avaliados 65 solos agrícolas representativos da região. Três formas lábeis de P foram medidas (Mehlich-1, Mehlich-3 e oxalato de amônio), e quatro índices de adsorção de P foram testados (adsorção de P em único ponto e Fe+Al obtido com os três extratores). O P extraível em água (PEA) foi utilizado como índice de suscetibilidade do P a perdas por escoamento superficial. O GSP foi obtido a partir do quociente entre a forma lábil de P e cada índice de adsorção. Os valores do GSP obtidos a partir do quociente entre P Mehlich-1 e a adsorção de P em único ponto variaram de 1 a 25%, enquanto os entre P Mehlich-1 e Fe+Al (oxalato de amônio) variaram de 1 a 55%. Todos os tipos de GSP estiveram altamente correlacionados ao PEA. Do ponto de vista de uso prático, o GSP obtido com P e Fe+Al extraídos com Mehlich-1 pode ser usado para estimar o risco de perda de P por escorrimento superficial em solos do Sul do Brasil.Termos para indexação: eutrofização, escorrimento superficial, P em único ponto, qualidade de água.

Section: Introductionmentioning

confidence: 99%

Degree of phosphorus saturation threshold for minimizing P losses by runoff in cropland soils of Southern Brazil

Ernani

et al. 2016

Pesq. agropec. bras.

“…Moreover, according MAGGI et al (2011), the result is also found linked to the fact that K + is a movable element in soil and is subjected to leaching. BERTOL et al (2010) reinforces this idea, stating that K + has low reactivity with soil which may cause an increased mobility. Previously, KING et al (1985) 2.58 - § Means followed by the same low case letter in the column do not differ by Tukey test at 5% significance for SWW and means followed by the same capital letter in the column do not differ by Tukey test at 5% significance for MF.…”

Section: Leachate Variablesmentioning

confidence: 60%

Swine wastewater associated with mineral fertilization on corn crop (Zea mays)

Kessler

Sampaio

Sorace³

et al. 2014

Eng. Agríc.

This study aimed to evaluate the agronomical and environmental aspects in corn, soil characteristics and leachate resulting from the material combination of swine wastewater and mineral fertilizer in the long run. The experimental area has a history of swine wastewater application for experiments conducted since 2006, this being the seventh crop cycle in the area. Four doses of swine wastewater (0; 100; 200 and 300 m 3 ha -1) associated with presence and absence of mineral fertilizer were applied, consisting of eight treatments. The results obtained were subjected to variance analysis and means compared by Tukey test at 5% significance. We conclude that the swine wastewater can be partially used as an alternative fertilizer, since the P and Mn are complemented with specific fertilization.

“…The surface-applied PS may be carried by runoff to watercourses, increasing P sol (Sharpley et al, 2003;Bertol et al, 2010;Gebler et al, 2012). The highest P sol concentrations were observed in W1 and the lowest in W4, which are the watersheds with the largest and smallest swine populations, respectively.…”

Section: Resultsmentioning

confidence: 99%

Relationships between Agriculture, Riparian Vegetation, and Surface Water Quality in Watersheds

Broetto

Tornquist

Campos

et al. 2017

Rev. Bras. Ciênc. Solo

ABSTRACT:Agricultural land use and degradation of natural vegetation in riparian zones can impair water quality. This study was conducted in seven agricultural watersheds in Ibirubá, RS, Brazil, with the following objectives: identify relationships between concentrations of soluble phosphorus (P sol ) and nitrate (NO − 3 ) in surface water and agricultural use of soil and current vegetation in riparian zones, and assess the risk of eutrophication. Water samples from the main watercourses in each watershed were collected monthly from 10/2013 to 6/2014. Current land use was established by field surveys in the watersheds. The riparian zones of the watercourses were evaluated in terms of the condition of permanent preservation area (PPA) and access of the animals to the watercourses. The concentration of P sol and NO − 3 were correlated with land use indicators obtained from geoprocessing tools. Agricultural use of PPA increases the risk of surface water degradation, which increases through application of manure on crops and free access of livestock to PPAs and to these watercourses for drinking water. Surface water samples obtained showed water P sol concentrations that generate risk of eutrophication, whereas concentrations of NO − 3 were generally below critical levels.