Comparative agroenvironmental risks of pesticides in different cropping systems: application of the I-Phy indicator

The green revolution laid the foundations of modern agriculture, by using science and technology to produce more from same resources. The pesticides contributed to agricultural output in the last decades; however, their use has resulted in environmental pollution, health problems, soil and water contamination and negative impact on biota. The impacts of agricultural activities to the environment depended on the practices adopted during the production process. Measurement tools to assess the impacts of those practices are necessary to improve agricultural systems and must be evaluated in different ecosystems. Different soils, climates and crops impose many phytosanitary arrangements. This complex network and the fact that most of the indicators and measurement tools are developed for temperate climates makes it difficult to quantify the environmental impacts under subtropical regions. The I-Phy index is a predictive indicator that assesses the risks of pesticide usage in agriculture and identifies as to which practices generate the main environmental impacts of pesticides. The objective of this study was to test the suitability of the I-Phy index for subtropical conditions and, if suitable, compare the pesticide risk between two regions. Five crops were assessed under three different cropping systems: no-tillage, minimal tillage and conventional tillage. The I-Phy index was sensitive in both regions and capable of identifying that no-tillage generally presented risks of environmental pollution slightly lower than the other tillage systems. The results of I-Phy index showed that high environmental vulnerability of the fields and the numerous applications of active ingredients with high risks resulted in high risks of general contamination. The application of I-Phy on these two case studies showed the indicator can be useful as a support tool to farmers, research and extension institutions pursuing management practices with lower impact on the environment

Differential effects of monomeric and polymeric aluminium on the root growth and on the biomass production of root and shoot of corn in solution culture

International audienc

Effect of Winter Cover Crop Biomass on Summer Weed Emergence and Biomass Production

A greenhouse assay was carried out to evaluate the effect of winter cover crop residues on spontaneous plants that commonly occur on summer annual fields in Southern Brazil. Dry shoot residues of rye (Secale cereale), vetch (Vicia villosa), fodder radish (Raphanus sativus), and a mix of the three species, were applied over pots that had been seeded with alexandergrass (Brachiaria plantaginea), hairy beggarticks (Bidens pilosa), wild poinsettia (Euphorbia heterophylla), and morning glory (Ipomoea grandifolia) at four different depths (0, 1, 2, or 4 cm). Plant emergence and biomass production were measured. Residues of rye reduced the emergence of B. plantaginea, while vetch diminished I. grandifolia and B. plantaginea emergence. Fodder radish reduced emergence of I. grandifolia. The mix of cover crops reduced emergence of I. grandifolia, B. plantaginea, and B. pilosa. None of the cover crops differed from the control on E. heterophylla emergence. The lowest yields in spontaneous plant shoot biomass were obtained from the cover with rye + vetch + fodder radish. The lowest values of root biomass occurred under cover with rye, fodder radish or the mix. Use of vetch residues decreased emergence of B. plantaginea and I. grandifolia, but enhanced biomass accumulation by the latter

Influence of the β parameter of the Haverkamp model on the transient soil water infiltration curve

International audienceSoil water infiltration can be described with the quasi-analytical Haverkamp et al. (1994) equation, defined by the hydraulic conductivity (Ks), sorptivity (S) and the β parameter. Ks and S are commonly estimated from the transient cumulative infiltration curve, using a constant β value. The objective of this work was to study the influence of β on the estimation of Ks and S. The study was first performed on synthetic 1-D infiltration curves generated at different infiltration times for loam sandy, loamy and silty soils, and next extrapolated to a 3-D loam synthetic soil and on 10 infiltrations curves measured on the field with a disc infiltrometer on different types of soils. The infiltration measurements lasted between 600 and 900 s. The results showed that, while early infiltration times (i.e. 100 s) promoted good estimations for S, longer infiltrations (i.e. 1.000 s) were required to estimate accurately Ks. Only very long infiltration (i.e. 10.000 s) allowed defining the actual β value. A similar behaviour was observed for the 3-D infiltration measurements. Except for β, significant relationships (R2 = 0.99) were obtained between the Ks and S of the three theoretical soils and the corresponding values calculated by optimizing the three hydraulic parameters on 2.000 s 1-D infiltration curves. The large confidence interval observed in β (between 0.3 and 2.0) resulted from the fact that β had a small effect on the infiltration curve. A significant relationship (R2 = 0.99) was also obtained between the Ks and S optimized from the experimental curves using a β = 1.1 and the corresponding values obtained by simultaneous optimization of the three hydraulic parameters. These results demonstrated that S and Ks can be accurately estimated using a constant β and that downward infiltration is not an appropriate procedure to estimate β

Nitrogen fertilization affects yield and fruit quality in pear

Mineralized nitrogen (N) from organic matter and decomposing residues in most soils are not always taken into account. Little is known about the correct N application dose for pear trees to promote yield and fruit quality, without increase the risk of N loss into the environment. The study aimed to evaluate the effect of N doses application on N soil content, tree yield and fruit quality. The treatments consisted of the application of 0, 40, 80, 120 and 160 kg N ha(-1) year(-1), whereas urea was applied on the soil surface in September and February for 5 seasons (2011/12 to 2015/16). Leaves were collected, prepared and submitted to nutrient analysis. Fruit weight, number and yield were evaluated. Soil samples were collected at 0-0.20 m for 3 seasons (2013/2014 to 2015/2016), prepared and submitted to NH4+-N and NO3-N analysis, and then mineral N content was calculated. Peel color, ethylene production, and respiration rate were analyzed in the 2015/2016 crop season after 90 days inside the controlled atmosphere storage chamber. The fruits were kept at ambient conditions for 7 days and evaluated again for peel color, ethylene production and respiration rate, as well as destructive parameters such as titratable acidity, soluble solids and pulp firmness. The doses of N application affect the fruit number and yield, but did not affect leaf nutrient concentration. The highest N levels in the soil were observed in the 2014/2015 and 2015/2016 crops. The most economical doses were 122.0, 66.4, 22.5 and 96.0 kg N ha(-1) in the crops of 2011/2012, 2012/2013, 2013/2014 and 2015/2016 respectivel

Nitrogen fertilization of ‘Chardonnay’ grapevines: yield, must composition and their relationship with temperature and rainfall

In soils rich in organic matter (OM), such as those in the elevations of South Brazil, the mineralized N from organic matter does not always meet the N demands of grapevines, thus, N applications are necessary during vine growth. However, the optimal N rate to achieve satisfactory yield and desirable grape enological composition is not known. The study aimed to evaluate yield and must composition of grapevine subjected to N applications, in relation to temperature and rainfall. The experiment was conducted in a vineyard planted in 2003 in the city of Água Doce, located in the Midwest region of the state of Santa Catarina, southern Brazil. The cultivar ‘Chardonnay’ grafted on rootstock 1103 Paulsen, planted in clay, high-OM soil was trained as a spur pruned cordon system. From 2011 to 2014, the grapevines were submitted to the application of N as urea at the following rates: 0, 20, 40, 80 and 120 kg N ha-1 split at bud sprout and full bloom. Leaves, collected at flowering and veraison, were dried, milled and analyzed for total N. At harvest, the number of clusters per plant and yield were recorded. Total soluble solids, titratable acidity, pH and tartaric acid were evaluated on must. Temperature and rainfall data were collected throughout the experiment. The application of N increased N concentration in leaves but had little effect on yield and must composition. According to principal component analysis, a negative correlation between rainfall and N in must was found. The highest N concentration in must was observed in crop season 2011/2012 with low rainfall; the opposite occurred in 2013/2014

Integração de técnicas de solo, plantas e animais para recuperar áreas degradadas Integration of techniques of soil, plants and animals for restoration of degraded areas

Este trabalho trata da recuperação de áreas degradadas pela mineração da fração argila em Doutor Pedrinho-SC. O estudo utilizou técnicas para integrar o solo, as plantas e os animais. Testaram-se dois níveis de topografia, regular e irregular, dois níveis de adubação, orgânica e química, e dois níveis de serapilheira, com e sem. A espécie arbórea selecionada foi a leguminosa Mimosa scabrella (bracatinga). Poleiros artificiais foram instalados na área a fim de incrementar o número de sementes provenientes de áreas vizinhas pelos devidos dispersores. Aos nove meses de avaliação, a partir das análises químicas de solo, não foram verificados incrementos nutricionais. A bracatinga apresentou índice de sobrevivência superior a 92%, enquanto que a cobertura do solo pela copa das árvores foi significativamente superior para os tratamentos que receberam serapilheira, com valores maiores de 67%. Apesar de a cobertura do solo pela revegetação natural não apresentar diferença, em geral, houve tendência da mesma ser maior nos tratamentos com topografia regular. Os poleiros artificiais foram responsáveis pela vinda de vinte e uma sementes pertencentes a seis morfoespécies distintas. Entre as doze famílias botânicas de plantas espontâneas identificadas, a maior parte apresentou síndrome de polinização zoofilica, dispersão de sementes anemocórica e hábito herbáceo. Conclui-se que a bracatinga, a abubação orgânica e/ou química, a serapilheira e os poleiros artificiais são indicados para utilização em programas de recuperação de áreas degradadas semelhantes ao deste estudo. Estudos complementares são necessários para avaliar a pertinência ou não do uso da topografia irregular em programas de recuperação de áreas degradadas.<br>This paper is about the restoration of areas degraded by clay mining in Doutor Pedrinho/ Brasil, state of Santa Catarina. The study employs techniques that integrate soil, plants and animals. Two types of surface preparation (regular and irregular), two types of fertilizer (organic and chemical), and two conditions of litter (present and absent) were tested. The species selected for the experiment was the legume Mimosa scabrella (bracatinga). Artificial perches were installed in the area in order to increase the amount of seeds from neighborhood areas. Chemical analysis of the soil, nine months after the initiation of the experiment, did not show any nutritional potential increase. The bracatinga showed a survival rate over 92%, whereas the soil cover by bracatinga canopies was significantly larger in the treatments where litter was added, with values over 67%. Although the soil cover by natural revegetation did not show any significant differences, it was in general larger in regular surface treatments. The artificial perches were responsible for bringing twenty one seeds from six distinct morpho species. Among the 12 identified botanical families, the larger part of them showed insect pollination, wind-dispersed seed and herbaceous habit. The conclusion is that the integrated use of bracatinga, organic and/or chemical fertilizer, litter and artificial perches are indicated for restoration programs in degraded areas similar to the one presented in this study. Further investigation is required to evaluate the relevance of the use of irregular surface in the restoration of degraded areas