Resumo Este estudo apresenta o resultado sobre a Disposição A PagaR (DAP) de Serviços Ecossistêmicos (SE) reguladores da água em uma bacia hidrográfica brasileira. O semiárido brasileiro é a maior região semiárida da América do Sul, esta área é classificada como o semiárido mais povoado do mundo. 393 questionários foram aplicados utilizando o Método de Avaliação Contingente (MVC). Dos inquiridos no território da bacia, mais de (77,9%) expressaram uma DAP positiva para manter os (SE) da Água. O pagamento pela conservação dos (SE) reguladores da água foi de R$ 10,00/mês, a qualidade da purificação da água pareceu ser um aspecto importante em termos do valor atribuído no pagamento. Por outro lado, os votos de protesto por não pagamento, que foram (22,1%), apontavam para o pagamento de muitos impostos. A (DAP) para a conservação da água foi definida pelo interesse ambiental e pela perda dos (SE) prestados da Caatinga.

Abstract This study presents the result on the Willingness To Pay (WTP) of Ecosystem Services (ES) regulating water a Brazilian watershed. The Brazilian semi-arid region is the largest semi-arid region in South America, this area is ranked as the most populated semi-arid region in the world. 393 questionnaires were applied using the Contingent Valuation Method (CVM). Of the respondents in the basin territory, over (77.9%) expressed a positive WTP for maintaining the (SE) of Water. The payment for the conservation of the (ES) water regulators was R$10.00/month, the quality of water purification seemed to be an important aspect in terms of the value assigned in the payment. On the other hand, the protest votes for non-payment, which were (22.1%), pointed to the payment of too many taxes. The (WTP) for water conservation was defined by environmental interest and the loss of the (SES) provided Caatinga.

ABSTRACT Increasingly rational use of phosphate fertilizers by agriculture is important, especially in Brazil, due to its importance for global food security and its high dependence on phosphate fertilizers for crop production. Thus, correlation and calibration researches with soil available phosphorus (P) extractants to improve the recommendation and the use of P are extremely important. Our objectives were (i) to determine soil P recovery rates and critical levels by the extractants Mehlich-1 (M1), Mehlich-3 (M3), and Ion Exchange Resin (RTI); (ii) to adjust predictive models of P recovery rates and critical levels for each extractant, as a function of soil properties related to the soil P buffer capacity, and (iii) to adjust the an interpretation table of soil P availability by M3 taking into account soil P buffer capacity indices. A pot experiment under greenhouse condition was conducted, in which the treatments were generated by the combination of a factorial 12 × 6, being 12 soil samples collected at a layer of 0.00-0.20 m, and six doses of P. The experimental units were constituted by plastic pots with capacity for 2.0 dm3 of soil, in which four hybrid corn plants (Zea mays L.) were cultivated for 45 d. The experimental design was a randomized complete block with four replicates. After cultivation, soil samples were collected from each experimental unit, and the determination of soil available P was performed by the extractants. The remaining P and the clay content were the soil properties that best correlated with the P recovery rates and P critical levels in the soil by the M1 and M3. The IER did not show sensitivity to soil P buffer capacity. The M3 had a discontinuous loss of extraction capacity with increasing soil P buffer capacity. Therefore, it is recommended the use of M3 as P extractant in soils with different characteristics, but a measure of soil P buffer capacity such as remaining P or clay content have to be used.

The shade leaves of coffee (Coffea arabica L.) apparently retain a robust photosynthetic machinery that is comparable to that of sun leaves and can fix CO2 at high rates when subjected to high light intensities. This raises the question of why the coffee plant would construct such a robust photosynthetic machinery despite the low photosynthetic rates achieved by the shade leaves at low light supply. Here, we grew coffee plants at 100% or 10% full sunlight and demonstrated that the shade leaves exhibited faster photosynthetic induction compared with their sun counterparts, in parallel with lower loss of induction states under dim light, and were well protected against short-term sudden increases in light supply (mimicking sunflecks). These findings were linked to similar photosynthetic capacities on a per mass basis (assessed under nonlimiting light), as well as similar extractable activities of some enzymes of the Calvin cycle, including Rubisco, when comparing the shade and sun leaves. On the one hand, these responses might represent an overinvestment of resources given the low photosynthetic rates of the shade leaves when light is limiting; on the other hand, such responses might be associated with a conservative behavior linked to the origin of the species as a shade-dwelling plant, allowing it to maximize the use of the energy from sunflecks and thus ultimately contributing to a positive carbon balance under conditions of intense shading.