The N-P-K soil nutrient balance of portuguese cropland in the 1950s: the transition from organic to chemical fertilization

Agricultural nutrient balances have been receiving increasing attention in both historical and nutrient management research. The main objectives of this study were to further develop balance methodologies and to carry out a comprehensive assessment of the functioning and nutrient cycling of 1950s agroecosystems in Portugal. Additionally, the main implications for the history of agriculture in Portugal were discussed from the standpoint of soil fertility. We used a mass balance approach that comprises virtually all nitrogen (N), phosphorus (P) and potassium (K) inputs and outputs from cropland topsoil for average conditions in the period 1951–56. We found a consistent deficit in N, both for nationwide (−2.1 kg.ha−1.yr−1) and arable crops (−1.6 kg.ha−1.yr−1) estimates, that was rectified in the turn to the 1960 decade. P and K were, in contrast, accumulating in the soil (4.2–4.6 kg.ha−1.yr−1 and 1.0–3.0 kg.ha−1.yr−1, respectively). We observed that the 1950s is the very moment of inflection from an agriculture fertilized predominantly through reused N in biomass (livestock excretions plus marine, plant and human waste sources) to one where chemical fertilizers prevailed. It is suggested that N deficiency played an important role in this transitioninfo:eu-repo/semantics/publishedVersio

Working landscapes need at least 20% native habitat

Abstract: International agreements aim to conserve 17% of Earth's land area by 2020 but include no area‐based conservation targets within the working landscapes that support human needs through farming, ranching, and forestry. Through a review of country‐level legislation, we found that just 38% of countries have minimum area requirements for conserving native habitats within working landscapes. We argue for increasing native habitats to at least 20% of working landscape area where it is below this minimum. Such target has benefits for food security, nature's contributions to people, and the connectivity and effectiveness of protected area networks in biomes in which protected areas are underrepresented. We also argue for maintaining native habitat at higher levels where it currently exceeds the 20% minimum, and performed a literature review that shows that even more than 50% native habitat restoration is needed in particular landscapes. The post‐2020 Global Biodiversity Framework is an opportune moment to include a minimum habitat restoration target for working landscapes that contributes to, but does not compete with, initiatives for expanding protected areas, the UN Decade on Ecosystem Restoration (2021–2030) and the UN Sustainable Development Goals

Rice actin binding protein RMD controls crown root angle in response to external phosphate

Root angle has a major impact on acquisition of nutrients like phosphate that accumulate in topsoil and in many species; low phosphate induces shallower root growth as an adaptive response. Identifying genes and mechanisms controlling root angle is therefore of paramount importance to plant breeding. Here we show that the actin-binding protein Rice Morphology Determinant (RMD) controls root growth angle by linking actin filaments and gravity-sensing organelles termed statoliths. RMD is upregulated in response to low external phosphate and mutants lacking of RMD have steeper crown root growth angles that are unresponsive to phosphate levels. RMD protein localizes to the surface of statoliths, and rmd mutants exhibit faster gravitropic response owing to more rapid statoliths movement. We conclude that adaptive changes to root angle in response to external phosphate availability are RMD dependent, providing a potential target for breeders

Water balance creates a threshold in soil pH at the global scale

Soil pH regulates the capacity of soils to store and supply nutrients, and thus contributes substantially to controlling productivity in terrestrial ecosystems. However, soil pH is not an independent regulator of soil fertility-rather, it is ultimately controlled by environmental forcing. In particular, small changes in water balance cause a steep transition from alkaline to acid soils across natural climate gradients. Although the processes governing this threshold in soil pH are well understood, the threshold has not been quantified at the global scale, where the influence of climate may be confounded by the effects of topography and mineralogy. Here we evaluate the global relationship between water balance and soil pH by extracting a spatially random sample (n = 20,000) from an extensive compilation of 60,291 soil pH measurements. We show that there is an abrupt transition from alkaline to acid soil pH that occurs at the point where mean annual precipitation begins to exceed mean annual potential evapotranspiration. We evaluate deviations from this global pattern, showing that they may result from seasonality, climate history, erosion and mineralogy. These results demonstrate that climate creates a nonlinear pattern in soil solution chemistry at the global scale; they also reveal conditions under which soils maintain pH out of equilibrium with modern climate

Positive co-operative interaction between the subunits of CeqI restriction endonuclease.

CeqI restriction endonuclease, an isoschizomer of EcoRV, forms complexes of 12-20 subunits under physiological conditions, in the absence of DNA. These molecules partially dissociate in the presence of DNA sequences recognized by CeqI or in the presence of non-ionic detergents. In solutions containing high concentrations of salts (e.g. 1 M-NaCl), the enzyme dissociates into subunits, concomitantly losing its activity. According to our experiments, it is the tetrameric form of the enzyme that binds the DNA and represents the catalytically active molecule. Analysis of the enzyme kinetics revealed a positive co-operative interaction between the subunits of the enzyme. Computer-assisted analysis of these data yielded a Hill coefficient of approx. 1.35, suggesting two binding sites per tetrameric enzyme molecule, two subunits per palindromic recognition site

Positive co-operative interaction between the subunits of CeqI restriction endonuclease.

CeqI restriction endonuclease, an isoschizomer of EcoRV, forms complexes of 12-20 subunits under physiological conditions, in the absence of DNA. These molecules partially dissociate in the presence of DNA sequences recognized by CeqI or in the presence of non-ionic detergents. In solutions containing high concentrations of salts (e.g. 1 M-NaCl), the enzyme dissociates into subunits, concomitantly losing its activity. According to our experiments, it is the tetrameric form of the enzyme that binds the DNA and represents the catalytically active molecule. Analysis of the enzyme kinetics revealed a positive co-operative interaction between the subunits of the enzyme. Computer-assisted analysis of these data yielded a Hill coefficient of approx. 1.35, suggesting two binding sites per tetrameric enzyme molecule, two subunits per palindromic recognition site