Evaluation of Organic Weed Management Practices on Growth, Yield and Weed Control Efficiency in Soybean-chickpea Sequence under Irrigated Condition

Background: Weeds are widely reported as a key constraint in organic agriculture. Soybean-chickpea is important cropping sequence adopted in Maharashtra State under irrigated condition. Weed management is a serious problem in both the crop and it mostly controlled through chemical weed control. Today, widespread use of herbicides has resulted in purporated environmental and health problem as well as residual problems to succeeding crops. Now a days residue free food requirement is high. In organic farming cultural and mechanical methods are necessary to break the weed cycle. So, keeping this point in view present investigation was carried out to evaluate organic weed management practices on growth, yield and weed control in soybean-chickpea sequence under irrigated condition. Methods: A field experiment was conducted during Kharif and rabi seasons of 2017-18 and 2018-19. The present investigation consisted of ten weed management practices viz. two hand weeding at 20-25 and 45-50 DAS, one hoeing 20-25 DAS + one hand weeding at 45-50 DAS, soybean + sunhemp incorporation after 35-40 DAS in kharif season and chickpea + safflower (2:1) in rabi season, stale seed bed + reduced spacing + 2 tonne of wheat straw + one hand weeding at 25 DAS, soil mulch at the time of sowing + one hand pulling at 25 DAS, incorporation of neem cake 1.5 tonne/ ha 15 days before sowing + one hand weeding at 25 DAS, soil solarization with 25 μ polythene mulch during summer + one hand weeding at 25 DAS, mulching with straw, weed free and weedy check. Result: The higher values of growth attributes was recorded by weed free treatment which was on par with two hand weeding at 20-25 and 45-50 DAS and soil solarization with 25 μ polythene mulch during summer + one hand weeding at 25 DAS and significantly superior over rest of the treatments during both the year study. Application of stale seed bed with reduced spacing and 2 tonne of wheat straw along with one hand weeding 25 DAS recorded higher soybean equivalent yield followed by soybean + sunhemp incorporation (35-45DAS) in kharif and chickpea + safflower (2:1) in rabi season during both the year. The lower weed density, dry weight and highest weed control efficiency at 40 days after sowing for both monocot and dicot weeds was recorded by weed free treatment followed by soil solarization with 25 μ polythene mulch during summer + one hand weeding at 25 DAS in soybean and chickpea during both the year.

Organic cotton production may alleviate the environmental impacts of intensive conventional cotton production

Conventional cotton production has been associated with the extensive use of agricultural chemicals, leading to environmental and health problems, decreased effectiveness of pesticides and higher costs of production. Organic bans the use of most pesticides while providing premiums for growers, and therefore may be a beneficial alternative for growers. Unfortunately, there has been a paucity of research examining the specific practices used by organic cotton growers and the environmental aspects of those practices. This study surveyed organic cotton producers and processors to document specific approaches and techniques used in organic cotton production and processing, the environmental impacts of those techniques and challenges facing organic cotton growers. We discuss the environmental impacts of organic management techniques and methods for conserving water and reducing dependence on irrigation. We also highlight the challenges to organic production identified in the survey, including management for weeds, insects and diseases, genetic contamination of organic crops from genetically modified cotton, organic seed availability, climate change, chemical drift and marketing of organic cotton. Finally, we suggest that investing in research to produce higher-yielding organic varieties, improved methods for organic weed management, and supporting carbon-sequestering practices will improve conversion to organic production.

Performance of Plant Aqueous Extracts for Organic Weed Management in Groundnut (Arachis hypogaea)

Different crops were raised and harvested at physiological maturity and weeds were collected at flowering stages during Kharif 2017 for preparing plant aqueous extracts at wet land farm of Sri Venkateswara Agricultural College, Tirupati. A field experiment was conducted to evaluate the performance of different plant aqueous extracts and paddy straw mulch for organic weed management in a randomized block design and replicated thrice during Rabi, 2017-18 and The predominant weed species observed were Cyperus rotundus L. (45%), Digitaria sanguinalis (L.) Scop. (15%), Borreria hispida (L.) K. Schum. (7%). All chemical weed management practices recorded significantly lesser weed density and dry weight than organic weed management practices. Among the organic weed management practice, application of paddy straw mulch at 5 t ha-1 recorded significantly lesser density and dry weight of weeds with higher weed control efficiency, apart from enhancing the yield components and pod yield of groundnut. Among the plant aqueous extracts, sorghum plant aqueous extract spray 15 L ha-1 at 15 and 30 DAS proved to be the best in controlling weeds and increasing pod yield. The performance of parthenium and purple nutsedge aqueous extracts each applied at 15 L ha-1 at 15 and 30 DAS were very poor in controlling weeds and promoting pod yield of groundnut. The reduction in pod yield of groundnut due to unchecked weed growth was 52.53 and 37.18% compared to pendimethalin 1kg ha-1 + HW at 30 DAS and paddy straw mulch at 5 t ha-1, respectively. Paddy straw mulch at 5 t ha-1 recorded significantly higher count of effective rhizobium nodules plant-1 and soil microorganisms viz., bacteria, fungi and actinomycetes.

Exploiting Olive Mill Byproducts and Other Waste for Organic Weed Management

Weed management represents one of the most serious and costly challenges in organic crop production systems. Agricultural waste/byproducts might present phytotoxicity that can be exploited to control weeds. Two experiments were designed to study the effects of four concentrations of olive vegetation water (OVW) and a control water treatment (with no OVW) on cheeseweed (Malva parviflora L.) seed germination in petri dishes and pots. In a third experiment, two rates of four composts (crop residue mix (CR), olive pomace (OP), dairy/horse manure (DM), and an OP/DM mix) were mixed into a clay‒loam soil at 0.10 or 0.20 L L−1, to assess their effects on weed number and biomass, in addition to bell pepper (Capsicum annuum L.) growth. In the petri dish experiment, the three highest OVW concentrations completely prohibited germination during the five-week duration of the study. For the pot experiment, 25 mL application of OVW significantly delayed and reduced cheeseweed germination, with the reduction being proportional to the concentration of OVW. In the third experiment, composts reduced weed dry matter (composed mostly of purslane (Portulaca oleracea L.)), with the CR compost being the most effective, reducing total weed biomass by 67% compared to the control. CR10 and DM10 tended to increase bell pepper yields, although none of the plant parameters was significantly affected by the compost treatments.

A Systems Comparison of Contrasting Organic Weed Management Strategies

Weed management strategies differ in their ability to control weeds, and often have unique agroecological implications. To provide growers with an improved sense of trade-offs between weed control and ecological effects, we implemented several prominent organic weed management strategies in yellow onion in 2014 and 2015. Strategies included cultivation of weed seedlings during the early, weed-sensitive “critical period” of the crop; frequent cultivation events to ensure “zero seed rain”; and weed suppression with polyethylene or natural mulches. As expected, end-of-season weed biomass and weed seed production were greatest in the critical period system and nearly zero for the zero seed rain system. Weeds were also well controlled in natural mulch systems. Average onion yield per treatment was 50.7 Mg ha−1. In 2014, the critical period system and the polyethylene mulch systems demonstrated yield loss, likely due to weed competition and excessive soil temperature, respectively. Onion soluble solids content was also diminished in these systems in 2014, but bulb firmness was greatest in unmulched systems. Carabid beetles, earthworms, soil compaction, soil nitrate, and microbial biomass were affected by weed management strategy, with natural-mulched systems generally performing most favorably. However, these effects were not substantial enough to affect yield of a subsequent sweet corn crop grown in weed-free conditions. In contrast, sweet corn managed with only early-season cultivations demonstrated yield loss (P=0.004) in plots where the critical period treatment was implemented the prior year, indicating that weed competition resulting from abundant weed seed production in that system was the most influential legacy effect of the weed management strategies.

A Survey of Weed Management in Organic Small Grains and Forage Systems in the Northwest United States

A lack of information regarding weed control, relative to conventional systems, has left organic growers largely on their own when devising weed management systems for organic crops. As interest in organic weed management increases, researchers need more information regarding the type and number of weed control practices undertaken on organic farms. A survey of certified organic growers was conducted in five states in the northwest United States to identify organic weed management programs and what grower and farm-operation characteristics were factors in weed management program design. Three types of weed management programs, with varying diversity in weed control practices, were identified. Stepwise binary logistic regression indicated that the likelihood of an organic grower using a more-diverse weed management program increased if the grower engaged in grain production and as the number of crops produced on an organic farm operation in 1 yr increased. The probability of operating a more-diverse weed management program also increased as a grower's education level increased. Organic hectarage operated was positively correlated with weed management program diversity, and with the adoption of cultural controls. Additionally, awareness of weeds as a factor causing yield loss was correlated with increased weed management program diversity. An increased awareness among researchers of the differing needs and abilities of organic growers in managing weeds on their farms will improve communication and outreach efforts when assisting growers with designing organic weed management programs.

Effects of Water on Recovery of Weed Seedlings Following Burial

Recovery of common agricultural weeds after burial by soil was studied in four greenhouse and three field experiments. Species studied included velvetleaf, Powell amaranth, common lambsquarters, barnyardgrass, and giant foxtail. Seedlings were bent over before burial to simulate the effect of the impact of soil thrown by a cultivator. Altogether, more than 35,000 seedlings were marked and observed for recovery. No seedlings recovered from 4 cm of burial. Recovery from complete burial under 2 cm of soil ranged from 0 to 24% depending on the experiment, species, and watering treatment, but recovery greater than 5% was rare. Large-seeded species tended to recover from complete burial under 2 cm of soil better than small-seeded species. The study did not reveal a difference in recovery of grasses relative to broadleaf weeds. Overall, seedlings tended to recover best when water was applied daily after burial, worst when water was applied once on the day of burial, and to an intermediate extent when no water was applied. However, difference in recovery between the no-water and watering-once treatments were usually small. Also, many experiment by species combinations showed no significant differences among watering treatments. When even a small portion of the seedling was left exposed, recovery generally exceeded 50%. Organic weed management systems commonly use burial of weed seedlings with tine weeders and soil thrown by sweeps and hilling disks to control weeds in crop rows. Recovery from burial could pose a substantial weed management problem in some circumstances, particularly for large-seeded weed species. Maximizing burial depth is important for limiting recovery. Recovery from burial can be minimized by withholding irrigation for several days after hilling-up operations.