Agro-ecological mechanisms for weed and pest suppression and nutrient recycling in high yielding complex rice systems

2021 ◽  
Vol 313 ◽  
pp. 107385
Author(s):  
Uma Khumairoh ◽  
Egbert A. Lantinga ◽  
Irfan Handriyadi ◽  
Rogier P.O. Schulte ◽  
Jeroen C.J. Groot
Toxics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 177
Author(s):  
Francisco Sánchez-Bayo

Pesticides released to the environment can indirectly affect target and non-target species in ways that are often contrary to their intended use. Such indirect effects are mediated through direct impacts on other species or the physical environment and depend on ecological mechanisms and species interactions. Typical mechanisms are the release of herbivores from predation and release from competition among species with similar niches. Application of insecticides to agriculture often results in subsequent pest outbreaks due to the elimination of natural enemies. The loss of floristic diversity and food resources that result from herbicide applications can reduce populations of pollinators and natural enemies of crop pests. In aquatic ecosystems, insecticides and fungicides often induce algae blooms as the chemicals reduce grazing by zooplankton and benthic herbivores. Increases in periphyton biomass typically result in the replacement of arthropods with more tolerant species such as snails, worms and tadpoles. Fungicides and systemic insecticides also reduce nutrient recycling by impairing the ability of detritivorous arthropods. Residues of herbicides can reduce the biomass of macrophytes in ponds and wetlands, indirectly affecting the protection and breeding of predatory insects in that environment. The direct impacts of pesticides in the environment are therefore either amplified or compensated by their indirect effects.


1988 ◽  
Vol 20 (8-9) ◽  
pp. 167-178
Author(s):  
O. M. Skulberg

Off-flavour substances may be regarded as a resource which can be used to study special ecological mechanisms. Relevant research on off-flavours is inextricably combined with the study of perception, ethology, genetic control etc. The chemicals concerned are commonly perceived by the senses of olfaction and gustation. Thus research on the chemical ecology of off-flavour substances in the aquatic environment involves the study of a variety of disciplines. For example the biochemistry of the relevant substances and appropriate metabolic pathways must be considered. Chemical properties are important for the behaviour of the substances. The production of off-flavours by organisms is related to phenological circumstances. The biotic effects of ecologically significant substances are dependent on several environmental factors. This paper draws attention to the possible application of fundamental research in this area to selected problems of ecological importance.


2017 ◽  
Vol 4 (2) ◽  
Author(s):  
SANJEEV KUMAR ◽  
SHIVANI . ◽  
S. K. SAMAL ◽  
S. K. DWIVEDI ◽  
MANIBHUSHAN .

Integration of different components viz. livestock, fishery, horticulture, mushroom etc. along with field crops not only enhanced productivity but by-products (waste) of one component act as input for another component through resource recycling within the system. Six integrated farming systems models with suitable combinations of Crop, vegetables, fruit trees, fish, livestock, mushroom etc. were made and evaluated at the experimental farm of ICAR Research Complex for Eastern Region, Patna during 2012-16 for harness maximum income, nutrient recycling and employment. Among six combinations, crop + fish + duck + goat resulted as most profitable combination in terms of productivity (RGEY- 22.2t), net income (Rs. 2,15,900/ha), additional employment (170 days/year) with income sustainability index (ISI) by 90.2. Upon nutrient recycling prepared from different wastes from the system Crop + fish + duck + goat combination added N (56.5 kg), P (39.6 kg) and K (42.7 kg) into the soil and reduced the cost of cultivation by 24 percent and was followed by crop + fish + goat combination. Crops grown under IFS mode with different types of manures produced 31 percent higher yield over conventional rice- wheat system. The contribution of crops towards the system productivity ranged from 36.4 to 56.2 %, while fish ranged from 22.0-33.5 %; for goat 25.4-32.9 %; for poultry 38.7 %; for duck 22.0-29.0 %; for cattle 32.2% and for mushroom 10.3 %.


2021 ◽  
Vol 289 ◽  
pp. 125708
Author(s):  
Sérgio Siqueira Amorim Junior ◽  
Valéria Sun Hwa Mazucato ◽  
Beatriz dos Santos Machado ◽  
Denilson de Oliveira Guilherme ◽  
Reginaldo Brito da Costa ◽  
...  

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Karin Holmfeldt ◽  
Emelie Nilsson ◽  
Domenico Simone ◽  
Margarita Lopez-Fernandez ◽  
Xiaofen Wu ◽  
...  

AbstractThe deep biosphere contains members from all three domains of life along with viruses. Here we investigate the deep terrestrial virosphere by sequencing community nucleic acids from three groundwaters of contrasting chemistries, origins, and ages. These viromes constitute a highly unique community compared to other environmental viromes and sequenced viral isolates. Viral host prediction suggests that many of the viruses are associated with Firmicutes and Patescibacteria, a superphylum lacking previously described active viruses. RNA transcript-based activity implies viral predation in the shallower marine water-fed groundwater, while the deeper and more oligotrophic waters appear to be in ‘metabolic standby’. Viral encoded antibiotic production and resistance systems suggest competition and antagonistic interactions. The data demonstrate a viral community with a wide range of predicted hosts that mediates nutrient recycling to support a higher microbial turnover than previously anticipated. This suggests the presence of ‘kill-the-winner’ oscillations creating slow motion ‘boom and burst’ cycles.


Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 531
Author(s):  
Gordon Port ◽  
Alan Craig ◽  
Mark Shirley

Following treatment with molluscicides or other controls, slugs can recolonize a site very quickly, but the proportion of the colonizing slugs moving from adjacent areas (horizontal dispersal) and the proportion from within the soil (vertical dispersal) has not previously been established. At a grassland site, barriers were used to exclude and trap slugs in order to estimate horizontal and vertical movement over a period of 32 months. For the first 15 months vertical movement made a significant contribution to the slugs recolonizing a grassland area. The ecological mechanisms occurring and the implications for the control of slugs are discussed.


Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1175
Author(s):  
Corinna Schröder ◽  
Franziska Häfner ◽  
Oliver Christopher Larsen ◽  
Ariane Krause

A transformation towards sustainable food production requires improved circular nutrient management. Urban organic waste contains relevant nutrients and organic matter, yet only 4% of global urban nitrogen (N) and phosphorus (P) sources are presently recycled. One recycling approach is the composting of urban wastes for urban horticulture. We characterized compost from various urban waste fractions and assessed their fertilizer value in a pot trial with lettuce plants. Seven treatments were investigated: food waste vermicompost with coir and paperboard bedding material, thermophilic compost from green waste and human feces, two references with mineral fertilization and a sand control. The lettuce yield and total uptake of P, potassium (K), calcium (Ca), and magnesium (Mg) were highest in plants grown in coir-based vermicompost. The fecal compost led to the highest shoot P and K content, but the shoot uptake of Ca and Mg were lower than in the other treatments. All composts required additional N for lettuce growth. In conclusion, urban waste-derived vermicompost and fecal compost demonstrate a high delivery rate of plant-available Ca, Mg, P, and K. Research is needed on macronutrient availability and alternative N sources for the substitution of synthetic fertilization. These findings support the production of urban waste composts, furthering efforts in nutrient recycling.


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