The Potassium Cycle and Its Relationship to Recommendation Development

Nutrient recommendation frameworks are underpinned by scientific understanding of how nutrients cycle within timespans relevant to management decision-making. A trusted potassium (K) recommendation is comprehensive enough in its components to represent important differences in biophysical and socioeconomic contexts but simple and transparent enough for logical, practical use. Here we examine a novel six soil-pool representation of the K cycle and explore the extent to which existing recommendation frameworks represent key plant, soil, input, and loss pools and the flux processes among these pools. Past limitations identified include inconsistent use of terminology, misperceptions of the universal importance and broad application of a single soil testing diagnostic, and insufficient correlation/calibration research to robustly characterize the probability and magnitude of crop response to fertilizer additions across agroecozones. Important opportunities to advance K fertility science range from developing a better understanding of the mode of action of diagnostics through use in multivariate field trials to the use of mechanistic models and systematic reviews to rigorously synthesize disparate field studies and identify knowledge gaps and/or novel targets for diagnostic development. Finally, advancing evidence-based K management requires better use of legacy and newly collected data and harnessing emerging data science tools and e-infrastructure to expand global collaborations and accelerate innovation.

Elevated atmospheric CO2 impact on carbon and nitrogen transformations and microbial community in replicated wetland

Background Elevated atmospheric CO2 has direct and indirect influences on ecosystem processes. The impact of elevated atmospheric CO2 concentration on carbon and nitrogen transformations, together with the microbial community, was evaluated with water hyacinth (Eichhornia crassipes) in an open-top chamber replicated wetland. The responses of nitrogen and carbon pools in water and wetland soil, and microbial community abundance were studied under ambient CO2 and elevated CO2 (ambient + 200 μL L−1). Results Total biomass for the whole plant under elevated CO2 increased by an average of 8% (p = 0.022). Wetlands, with water hyacinth, showed a significant increase in total carbon and total organic carbon in water by 7% (p = 0.001) and 21% (p = 0.001), respectively, under elevated CO2 compared to that of ambient CO2. Increase in dissolved carbon in water correlates with the presence of wetland plants since the water hyacinth can directly exchange CO2 from the atmosphere to water by the upper epidermis of leaves. Also, the enrichment CO2 showed an increase in total carbon and total organic carbon concentration in wetland soil by 3% (p = 0.344) and 6% (p = 0.008), respectively. The total nitrogen content in water increased by 26% (p = 0.0001), while total nitrogen in wetland soil pool under CO2 enrichment decreased by 9% (p = 0.011) due to increased soil microbial community abundance, extracted by phospholipid fatty acids, which was 25% larger in amount than that of the ambient treatment. Conclusion The study revealed that the elevated CO2 would affect the carbon and nitrogen transformations in wetland plant, water, and soil pool and increase soil microbial community abundance.

Penerapan Jantanisasi Ikan Nila (Oreochromis niloticus) di Kelompok Tani Kahayan Mina Kelurahan Pahandut Seberang Kecamatan Pahandut Kota Palangka Raya

Community Service program Kahayan Mina fish farmers group in Pahandut Seberang Village, Pahandut Subdistrict, Palangka Raya City in the form of an effort to implement masculinization cultivation technology on tilapia (Oreochromis niloticus) in soil ponds with the aim of increasing the knowledge and skills of target audiences and their benefits. New micro for target partners. Method of activity with the purpose of direct participant observation and interviews, training, technical guidance and demonstration plot demonstration area. The results of the Community Service program in the Kahayan Mina fish cultivator group in cultivating Tilapia in the soil pool can understand and know the tilapia fish maintenance techniques with a maleization/masculinization system.

The Evolutionary Moulding in plant-microbial symbiosis: matching population diversity of rhizobialnodA and legumeNFR5genes

We propose the Evolutionary Moulding hypothesis that population diversities of partners in nitrogen-fixing rhizobium-legume symbiosis are matched, and tested it in nucleotide polymorphism of symbiotic genes encoding two components of the plant-bacteria signalling system. The first component is the rhizobialnodA acyltransferase involved in the fatty acid tail decoration of Nod factor (rhizobia signalling molecule). The second component is the plantNFR5receptor, putatively required for Nod-factor binding.We collected three wild growing legume species together with soil samples adjacent to the roots (soil pool) from one large 25-year fallow:Vicia sativa, Lathyrus pratensisandTrifolium hybridumnodulated by one of the twoRhizobium leguminosarumbiovars (viciaeandtrifolii). For each plant species we prepared three pools for DNA extraction: the plant pool (30 plant indiv.), the nodule pool (90 nodules) and the soil pool (30 samples).NFR5gene libraries from the plant pool andnodA gene libraries from nodule and soil pools were sequenced by Sanger technology and High-throughput pyrosequencing, respectively. Analysis of the data demonstrated concordance in population diversities of one symbiotic partner (rhizobia) the second partner (legume host), in line with the Evolutionary Moulding hypothesis. This effect was evinced by the following observations for each plant species: (1) significantly increased diversity in the nodulenodA popset (set of gene sequences derived from the nodule population) compared to the soil popset; (2) a monotonic relationship between the diversity in the plantNFR5gene popset and the nodule rhizobialnodA gene popset; and (3) higher topological similarity of theNFR5gene tree with thenodA gene tree of the nodule popset, than with thenodA gene tree of the soil popset. Both nonsynonymous diversity and Tajima’s D were increased in the nodule popsets compared to the soil popsets, consistent with relaxation of negative selection and/or admixture of balancing selection underlying the Evolutionary Moulding effect. We propose that the observed genetic concordance arises from the selection of particular characteristics of the nodulenodA genes by the host plant.

Decomposition and release of nutrients from leaf litter in rubber plantations

<p>Establishment of cover crop has been a standard scientific agronomic intervention in rubber (<em>Hevea brasiliensis</em>) plantations. Natural leaf fall in rubber plantations is an unaccounted phenomenon which also improves the physicochemical properties and biological activities of soil. A comparison of the decomposition of leaf litter from different sources in soil and the release of utrients from them has been attempted in this study through a field experiment. Studies indicated that the degradation and release of nutrients to the soil pool was mainly decided by the leaf chemistry and degradability of the litter. Rubber litter had its own edge over other leguminous cover crop litter, in providing a sustained release of potassium, calcium and magnesium owing to its slow and steady mineralization rate compared to cover crops. Higher content of nutrients was recorded in degraded litter in comparison to fresh sources. Legume cover crops are capable of enhancing the bacterial and fungal populations in soil compared to nonleguminous crops in rubber plantations.</p>

Processes regulating progressive nitrogen limitation under elevated carbon dioxide: a meta-analysis

Nitrogen (N) cycle has the potential to regulate climate change through its influence on carbon (C) sequestration. Although extensive researches have been done to explore whether or not progressive N limitation (PNL) occurs under CO2 enrichment, a comprehensive assessment of the processes that regulate PNL is still lacking. Here, we quantitatively synthesized the responses of all major processes and pools in terrestrial N cycle with meta-analysis of CO2 experimental data available in the literature. The results showed that CO2 enrichment significantly increased N sequestration in plant and litter pools but not in soil pool. Thus, the basis of PNL occurrence partially exists. However, CO2 enrichment also significantly increased the N influx via biological N fixation, but decreased the N efflux via leaching. In addition, no general diminished CO2 fertilization effect on plant growth over time was observed. Overall, our analyses suggest that the extra N supply by the increased biological N fixation and decreased leaching may potentially alleviate PNL under elevated CO2 conditions. Moreover, our synthesis showed that CO2 enrichment increased soil ammonium (NH4+) but decreased nitrate (NO3-). The different responses of NH4+ and NO3-, and the consequent biological processes, may result in changes in soil microenvironment, community structures and above-belowground interactions, which could potentially affect the terrestrial biogeochemical cycles and the feedback to climate change.

Processing Properties of Grains from some Maize Varieties Introduced On-farm in the Sudano Sahelian Zone of Cameroon

Maize grains from twenty three cultivars developed by research and produced at farm level were evaluated for chemical composition and their ability to produce flour and grit after removal of panicle in wet and dry processes. Sixteen cultivars used for this evaluation were developed by the breeding program of the Institute of Agricultural Research for Development (IRAD) of Cameroon. The remaining seven originated from CIMMYT, West and Central Africa Maize Network (Wecaman), Ghana and Congo. Flour and grit were produced in wet and dry processes with samples of 10 kg of grains from each cultivars using available machinery at village level. Wet process of the grains included the removal of the panicle, soaking for 3 hours, drying on the mat for 2 hours, milling, drying of the flour and sieving through different mesh sizes (400 to 800 microns). For the dry milling, whole or pealed grains were simply processed in a hammer mill and the flour fractions separated as with wet milling. Results indicated some variation in the proximate composition with nine cultivars exhibiting protein contents above 8%. High protein cultivars were in order hybrids 88094X87036, 87036XExp124, Acid soil pool yellow, 88094XM131XExp124, 87084XM131XExp124, Drought pool yellow, Drought pool white, Kassaï SR, Tuxpeno sequia and BSR 81. PCA analyses revealed that protein and fat contents as factors accounted for over 80% of intra cultivar variability related to chemical composition. Four major similarity groups of cultivars emerged as striga tolerant with high starch contents, the soft endosperm cultivars, the high fat and high protein cultivars. Flour and grit yields were cultivar and treatment dependant. Wet milling produced higher flour yields while grit yields were higher when dry milling of pealed grains was done for all cultivars. Cultivars that demonstrated good ability for grit production were ATP SR-Y, Acid soil pool yellow, Drought pool yellow and the hybrids. All cultivars exhibited their ability and suitability for different end uses and this should be taken into account when embarking on large scale maize production.