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Nutrient additions to intensive agricultural systems range from inadequate to excessive—and both extremes have substantial human and environmental costs. Nutrient cycles link agricultural systems to their societies and surroundings; inputs of nitrogen and phosphorus in particular are essential for high crop yields, but downstream and downwind losses of these same nutrients diminish environmental quality and human well-being. Agricultural nutrient balances differ substantially with economic development, from inputs that are inadequate to maintain soil fertility in parts of many developing countries, particularly those of sub-Saharan Africa, to excessive and environmentally damaging surpluses in many developed and rapidly growing economies. National and/or regional policies contribute to patterns of nutrient use and their environmental consequences in all of these situations ( 1 ). Solutions to the nutrient challenges that face global agriculture can be informed by analyses of trajectories of change within, as well as across, agricultural systems.

Soils are increasingly recognized as major contributors to ecosystem services such as food production and climate regulation (1, 2), and demand for up-to-date and relevant soil information is soaring. But communicating such information among diverse audiences remains challenging because of inconsistent use of technical jargon, and outdated, imprecise methods. Also, spatial resolutions of soil maps for most parts of the world are too low to help with practical land management. While other earth sciences (e.g., climatology, geology) have become more quantitative and have taken advantage of the digital revolution, conventional soil mapping delineates space mostly according to qualitative criteria and renders maps using a series of polygons, which limits resolution. These maps do not adequately express the complexity of soils across a landscape in an easily understandable way

To feed the world without further damaging the planet, Jeffrey Sachs and 24 food-system experts call for a global data collection and dissemination network to track the myriad impacts of different farming practices.

The combination of advances in knowledge, technology, changes in consumer preference and low cost of manufacturing is accelerating the next technology revolution in crop, livestock and fish production systems. This will have major implications for how, where and by whom food will be produced in the future. This next technology revolution could benefit the producer through substantial improvements in resource use and profitability, but also the environment through reduced externalities. The consumer will ultimately benefit through more nutritious, safe and affordable food diversity, which in turn will also contribute to the acceleration of the next technology. It will create new opportunities in achieving progress towards many of the Sustainable Development Goals, but it will require early recognition of trends and impact, public research and policy guidance to avoid negative trade-offs. Unfortunately, the quantitative predictability of future impacts will remain low and uncertain, while new chocks with unexpected consequences will continue to interrupt current and future outcomes. However, there is a continuing need for improving the predictability of shocks to future food systems especially for ex-ante assessment for policy and planning.

Let 𝑆₁ and 𝑆₂ be two affine semigroups, and let 𝑆 be the gluing of 𝑆₁ and 𝑆₂. Several invariants of S are related to those of 𝑆₁ and 𝑆₂; we review some of the most important properties preserved under gluings. The aim of this paper is to prove that this is the case for the Frobenius vector and the Hilbert series. Applications to complete intersection affine semigroups are also given.

Processes catalyzed by enzymes offer numerous advantages over chemical methods although in many occasions the stability of the biocatalysts becomes a serious concern. Traditionally, synthesis of nucleosides using poorly water-soluble purine bases, such as guanine, xanthine, or hypoxanthine, requires alkaline pH and/or high temperatures in order to solubilize the substrate. In this work, we demonstrate that the 2′-deoxyribosyltransferase from Leishmania mexicana ( Lm PDT) exhibits an unusually high activity and stability under alkaline conditions (pH 8–10) across a broad range of temperatures (30–70 °C) and ionic strengths (0–500 mM NaCl). Conversely, analysis of the crystal structure of Lm PDT together with comparisons with hexameric, bacterial homologues revealed the importance of the relationships between the oligomeric state and the active site architecture within this family of enzymes. Moreover, molecular dynamics and docking approaches provided structural insights into the substrate-binding mode. Biochemical characterization of Lm PDT identifies the enzyme as a type I NDT (PDT), exhibiting excellent activity, with specific activity values 100- and 4000-fold higher than the ones reported for other PDTs. Interestingly, Lm PDT remained stable during 36 h at different pH values at 40 °C. In order to explore the potential of Lm PDT as an industrial biocatalyst, enzymatic production of several natural and non-natural therapeutic nucleosides, such as vidarabine (ara A), didanosine (ddI), ddG, or 2′-fluoro-2′-deoxyguanosine, was carried out using poorly water-soluble purines. Noteworthy, this is the first time that the enzymatic synthesis of 2′-fluoro-2′-deoxyguanosine, ara G, and ara H by a 2′-deoxyribosyltransferase is reported.

Improved fallows are the deliberate planting of fast-growing species -- usually legumes -- for rapid replenishment of soil fertility. Improved fallows are rapidly spreading in several regions of the tropics as a sensible way for in situ accumulation of large quantities of N in vegetation and soil, as well as for providing sustainability enhancing services. Research on improved fallows increased after the mid 1980s with the development of what is known as the second soil fertility paradigm, which is based on sustainability considerations. Many lessons have emerged from short-term improved fallows (<5 years duration). These include the diversity of farm sizes where improved fallows are used, the advantage of sequential versus simultaneous systems, the utilization of dry seasons unfavorable for crop production, the comparative advantages of woody versus herbaceous leguminous fallows, the magnitude of N accumulation, the strategic use of N fertilizers, and the importance of P. Other key services provided by fallows include fuelwood production, recycling of nutrients besides N, provision of a C supply to soil microorganisms, weed suppression, Striga control, and improved soil water storage. Natural fallows of non-legume shrubs belonging to the Asteraceae family, collectively called 'daisy fallows', may provide lessons for the development of improved fallows. The maintenance of genetic diversity in fallows is paramount. The main limiting factor in Africa is clearly the supply of germplasm of improved fallow species. This must be overcome though large-scale seed orchards and nursery development before impact at the scale of millions of farmers can take place.[PUBLICATION ABSTRACT]

Information on decomposition and nitrogen release patterns of tropical legumes is scarce despite the important role of legumes in agroforestry systems. Decomposition patterns of the leaves of three tropical legumes Inga edulis Mart., Cajanus cajan (1.) Millsp., and Erythrina sp. were determined by a litterbag study in an alley cropping experiment conducted in the Peruvian Amazon. The leaflets of the three species had similar nitrogen concentrations but different lignin and soluble polyphenolic concentrations. Inga and Cajanus decomposed at similar rates (k = 0.91 and 1.72 yr$^{-1}$, respectively) and had similar polyphenolic concentrations but differed in lignin. Erythrina had the lowest concentration of polyphenolics and decomposed the fastest (k = 3.45 yr$^{-1}$). Polyphenolics appeared to influence rates of decomposition more than percent nitrogen or percent lignin. It is proposed that the polyphenolics bind to N in the leaves forming compounds resistant to decomposition. These compounds may be precursors to stable forms of nitrogen in soil organic matter. Rates of nutrient loss followed the general trend potassium > phosphorus, nitrogen, and magnesium > calcium. It is apparent from this study that not all leguminous leaves decompose and release nitrogen quickly, despite high nitrogen concentrations in the leaves. Nitrogen release by legumes with high polyphenolic concentrations will be slower than that by legumes with low polyphenolic concentrations and has important implications to nitrogen cycling and the selection of legumes for agroforestry systems.