Management of Nitrogen Flow in Livestock Waste System Towards an Efficient Circular Economy in Agriculture.

The race is on to achieve high level of efficiency in the attainment of circular economy in Agriculture especially with the aim of sustainable nitrogen management. This cycle in the agricultural sector cuts across livestock farming, agriculture induced waste generation, recycling and utilization, energy generation, crop production, ecosystem protection and environmental management through the mitigation of climate changes. In this work, we access the process and functionalities of livestock waste generated from the piggery farm and the combinations with other by-products such as biochar and ash in comparison with mineral fertilisation (MN) as sources of nitrogen (N) applied in agricultural soil. The experiment was performed in a controlled environment with wheat (Triticum aestivum L.) grown in a neutral and an acidic soil. Pig manure was used as the primary feedstock, fed, and processed to biogas and nutrient rich digestate by anaerobic digestion process. The digestate generated were amended with biochar and ash. In the course of the cultivation period, pig manure digestate with other co-amendments showed a positive influence on mobile potassium and phosphorus contents, biomass yield and nitrogen use efficiency. Greenhouse gas (GHG) emissions in the form of methane, carbon dioxide and nitrous oxide released in both soil types from the amendments were significantly lower when compared to mineral nitrogen treatment. The amendments did not have any significant influence on dehydrogenase activity, especially in the acid soil with the pH negatively influencing the enzymatic activities. The pig manure and pig manure digestate treatments showed positive response in the soil microbial biomass-C in the two soil types when compared to other co-amendments. Application of single use amendment application or in combination with biochar and ash as a means of waste management can enhance the N flow to meet up with crop needs, reduce GHG emissions and reduce potential agriculture’s negative environmental footprint.

Immigration dynamics of tropical and subtropical Southeast Asian limestone karst floras

Ex situ origins and dispersal of taxa have played important roles in the assembly of island-like biodiversity hotspots. Insular limestone karsts in Southeast Asia are hotspots of biodiversity and endemism, but the immigration processes of their unique floras are still poorly known. Here, we used Gesneriaceae as a proxy to investigate the immigration dynamics of tropical and subtropical Southeast Asian karst floras. We present the most comprehensive phylogenetic analysis of the Old World gesneriads to date based on twelve loci. By estimating divergence times and reconstructing ancestral states (habitat, soil type and range), we found that immigration into subtropical Southeast Asian karst floras first occurred in the Early Miocene, with two peaks in the Early–Middle Miocene and the Pliocene–Early Pleistocene, whereas immigration into tropical Southeast Asian karsts initiated in the Late Eocene, with two peaks in the Late Oligocene and the Late Miocene. We also discover that Southeast Asian karst biodiversity comprises immigrant pre-adapted lineages and descendants from local acid soil ancestors, although niche shift from acid soil to karst in tropical Southeast Asian islands was lacking. This study advances our understanding of the historical assembly of Southeast Asian karst floras.

Nitrogen released from sago pulp waste and Gliricidia sepium pruning mixtures on a Dystrudept of Central Moluccas and its effect on the growth of maize

The agricultural sector is the mainstay of the economy in Central Moluccas. However, most agricultural soils on the island have low soil fertility. One of the efforts that farmers can make to improve soil fertility is to apply organic matter, which is widely found in Central Moluccas. This study aimed at elucidating the effect of mixing high-quality organic material (Glicidia sepium pruning) with low-quality organic material (sago pulp waste) on the improvement of available nitrogen in an acid soil (Dystrudept) and growth of maize. Two experiments were carried out in a laboratory and a greenhouse. The compositions of the mixtures of sago pulp waste (A) and pruning of Gliricidia sepium (G) were A0 G100; A20G80; A40G60; A60G40; A80G20, and A100G0. Six treatments and one control (no application of residues) were arranged in a completely randomized design. The results showed that the application of the mixture of 20% and 80% of Gliricidia sepium pruning (A20G80) increased the cumulative amount of mineral N in the soil higher than that of the other organic material mixtures, which in turn improved maize growth.

Physiological Characteristics of Cultivated Tepary Bean (Phaseolus acutifolius A. Gray) and Its Wild Relatives Grown at High Temperature and Acid Soil Stress Conditions in the Amazon Region of Colombia

Common bean (Phaseolus vulgaris L.) is sensitive to different types of abiotic stresses (drought, high temperature, low soil fertility, and acid soil), and this may limit its adaptation and consequently to its yield under stress. Because of this, a sister species, tepary bean (Phaseolus acutifolius A. Gray), has recently gained attention in breeding for improved abiotic stress tolerance in common bean. In this study, we evaluated the adaptation of 302 accessions of tepary bean (Phaseolus acutifolius A. Gray) and its wild relatives (grouped in four types of tepary bean genetic resource: cultivated, acutifolius regressive, acutifolius wild, tenuifolius wild) when grown under high temperature and acid soil conditions with aluminum toxicity in the Amazon region of Colombia. Our objective was to determine differences among four types of tepary bean genetic resource in their morpho-phenological, agronomic, and physiological responses to combined high temperature and acid soil stress conditions. We found that cultivated P. acutifolius var acutifolius presented a greater number of pods per plant, as well as larger seeds and a greater number of seeds per pod. Some traits, such as root biomass, days to flowering and physiological maturity, specific leaf area, and stomatal density, showed significant differences between types of tepary bean genetic resource, probably contributing to difference in adaptation to combined stress conditions of high temperature and acid soil conditions. The photochemical quenching (qP) was higher in cultivated P. acutifolius var. acutifolius, while energy dissipation by non-photochemical quenching (NPQ) in the form of heat and the coefficient of non-photochemical dissipation (qN) were higher in acutifolius regressive and tenuifolius wild accessions. We have identified 6 accessions of cultivated and 19 accessions of tenuifolius wild that exhibited grain yields above 1800 kg ha−1. These accessions could be suitable to use as parents to improve dry seed production of tepary bean under combined stress conditions of high temperature and acid soil.

Integration of Small RNA and Degradome Sequencing Reveals the Regulatory Network of Al-Induced Programmed Cell Death in Peanut

Peanut is one of the most important oil crops in the world. In China, the peanut is highly produced in its southern part, in which the arable land is dominated by acid soil. At present, miRNAs have been identified in stress response, but their roles and mechanisms are not clear, and no miRNA studies have been found related to aluminum (Al)-induced programmed cell death (PCD). In the present study, transcriptomics, sRNAs, and degradome analysis in the root tips of two peanut cultivars ZH2 (Al-sensitive, S) and 99-1507 (Al-tolerant, T) were carried out. Here, we generated a comprehensive resource focused on identifying key regulatory miRNA-target circuits that regulate PCD under Al stress. Through deep sequencing, 2284 miRNAs were identified and 147 miRNAs were differentially expressed under Al stress. Furthermore, 19237 target genes of 749 miRNAs were validated by degradome sequencing. GO and KEGG analyses of differential miRNA targets showed that the pathways of synthesis and degradation of ketone bodies, citrate cycle (TCA cycle), and peroxisome were responded to Al stress. The combined analysis of the degradome data sets revealed 89 miRNA-mRNA interactions that may regulate PCD under Al stress. Ubiquitination may be involved in Al-induced PCD in peanut. The regulatory networks were constructed based on the differentially expressed miRNAs and their targets related to PCD. Our results will provide a useful platform to research on PCD induced by Al and new insights into the genetic engineering for plant stress response.

Effects of Modification and Co-Aging with Soils on Cd(II) Adsorption Behaviors and Quantitative Mechanisms by Biochar

In this study, original rice straw biochar and two KMnO4-modified biochars (pre- and postmodification) were prepared, which were all pyrolysed at 400℃. Premodified biochar had the largest Cd adsorption capacity, strongest acid and solute buffering capacity, which benefited from the increase of carbonate content, specific surface area and the emergence of Mn(II) and MnOx through modification. Original and premodified biochars were then conducted four types of aging process, namely, aging without soil, co-aging with acid (pH=5.00), neutral (pH=7.00) and alkaline (pH=8.30) soils, using an improved three-layer mesh method. The adsorption capacities of modified biochar were always larger than those of original biochar after aging processes. After four aging processes, Cd(II) adsorption capacities were basically in the order of aged biochar without soil > biochar co-aged with alkaline soil > biochar co-aged with neutral soil > biochar co-aged with acid soil, and KMnO4-modified biochar was always better than original biochar after co-aging with soils. The dominant adsorption mechanism of original and premodified biochars (fresh and aged) for Cd(II) was all the precipitation and adsorption with minerals (accounted for 58.55%~85.55%). In this study, we highlighted that biochar remediation for Cd should be evaluated by co-aging with soil instead of aging without soil participation.

Effect of Integrated Nutrient Management on Okra Production in Acid Soil

Integrated Nutrient Management (INM) is a novel strategy to achieve sustainable crop production in degraded soils through judicious and balanced plant nutrients utilization. Sole application of chemical fertilizers in crop production causes soil and environmental pollution. The present study was designed to assess the effects of application of organic manures conjointly with chemical fertilizers on growth and yield of okra in acid soil. The experiment was consisted of four treatments viz. T0 [Control], T1 [Recommended dose of chemical fertilizers (RDF)], T2 [Dolomite (D) @ 1t ha-1 + RDF], T3 [Poultry manure (PM) @ 3t ha-1 + RDF], T3 [Cow dung (CD) @ 5t ha-1 + RDF] with six replications in a randomized complete block design. The results indicated that the use of PM with RDF showed better performance in the growth and yield attributes of okra. Compared with others plots, the highest plant height (114.10 cm), fresh weight plant-1 (591.58 g) and dry weight plant-1 (86.73 g) were observed in the PM-treated plot. Similarly, the highest number of fruits plant-1 (20.33) and fruit yield (13.58 t ha-1) were also found in PM-treated plants. Therefore, under acidic soil conditions, organic and inorganic fertilization may have a significant positive impact on the growth and yield of Okra.