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Realizing van der Waals (vdW) epitaxy in the 80s represents a breakthrough that circumvents the stringent lattice matching and processing compatibility requirements in conventional covalent heteroepitaxy. However, due to the weak vdW interactions, there is little control over film qualities by the substrate. Typically, discrete domains with a spread of misorientation angles are formed, limiting the applicability of vdW epitaxy. Here we report the epitaxial growth of monocrystalline, covalent Cr5Te8 2D crystals on monolayer vdW WSe2 by chemical vapor deposition, driven by interfacial dative bond formation. The lattice of Cr5Te8, with a lateral dimension of a few ten microns, is fully commensurate with that of WSe2 via 3 x 3 (Cr5Te8)-7 x 7 (WSe2) supercell matching, forming a single crystalline moire superlattice. Our work has established a conceptually distinct paradigm of thin film epitaxy termed dative epitaxy, which takes full advantage of covalent epitaxy with chemical bonding for fixing the atomic registry and crystal orientation, while circumventing its stringent lattice matching and processing compatibility requirements; conversely, it ensures the full flexibility of vdW epitaxy, while avoiding its poor orientation control. Cr5Te8 2D crystals grown by dative epitaxy exhibit square magnetic hysteresis, suggesting minimized interfacial defects that can serve as pinning sites.

Jatropha curcas L. is a plant species from the family of Euphorbiaceae. The extraction of oil from its seeds produces a cake for which its accumulation causes different environmental problems related to solid waste management. The valorization of this cake into compost could be a contribution to solving this problem. Therefore different types of compost were made with J. curcas seed cake associated with animal feces incorporated at 0, 10 and 20% rate. To achieve their combination, 5 composting test and 2 replicates each have been set up. These composts were tested on cabbage yield in a completely randomized design with 6 treatments and 3 replicates. The different composts have improved significantly the chemical characteristics of the soil and the cabbage biomass yield. Mixing J. curcas seed cake with 10% sheep’s droppings (C10) gave chemical characteristics compost with a high N and K content (Total-N 18.32 g.kg-1; Total-K 17.60 g.kg-1). The compost made with J. curcas seed cake and 20% sheep’s droppings (C20) had the best cabbage total biomass and shoots of cabbage biomass yields respectively 43.11±3.15×103 and 21.56±1.58×103kg.ha-1. That compost C20 could be recommended to farmers for the improvement of crop yield field after trials followed by validation. Key words: Jatropha curcas, seed cake, compost, cabbage shoot yield.

It is essential to produce optimal crop yields while reducing adverse environmental impacts of overfertilization. Therefore, nutrient-efficient plants may play a major role in improving the efficiency of fertilizer use whilst increasing crop yields. This field trial was conducted to study the differences on absorption and utilization of nitrogen (N), phosphorus (P), and potassium (K) of K-efficient cotton genotype 103 and K-inefficient cotton (Gossypium hirsutum L.) genotype 122 and their environmental and economic effects. The results show that seed cotton yield was significantly different between K-efficient cotton genotype 103 and K-inefficient cotton genotype 122; the yields of genotype 103 were 39.2%, 33.8%, and 25.0% higher than those of genotype 122 with no K fertilizer (K0), 112 kg K ha–1 K (K1), and 224 kg K ha–1 (K2), respectively. Even when no K fertilizer was applied, the yield of genotype 103 was still 7.9% higher than the yield of genotype 122 at the highest K level (K2). Further economic benefit analysis revealed that the value cost ratio (VCR) of genotype 103 was significantly higher than 122 at K0 and K1, and harvest index (HI) of genotype 103 was significantly higher than that of genotype 122 at all three K levels. In addition, when fertilized with K, partial factor productivity of applied K (PFPK) of genotype 103 was dramatically higher than that of genotype 122, demonstrating that genotype 103 had stronger ability to utilize K. Besides, the N- and P-use efficiencies of genotype 103 were also higher than those of genotype 122. It is concluded that: (1) genotype 103 gives better profit than genotype 122 and (2) genotype 103 uses fertilizer more efficiently and reduced fertilizer inputs will alleviate environmental risks.