Effects of Rape Residue as Green Manure on Rice Growth and Weed Suppression

AbstractGreen manure crops must produce high biomass to supply biological N, increase organic matter and control weeds. The objectives of our study were to assess above-ground biomass productivity and weed suppression of clover (Trifolium spp.) green manures in an organic soybean [Glycine max (L.) Merr.]-winter wheat (Triticum aestivum L.)-corn (Zea mays L.) rotation in eastern Nebraska in three cycles (2011–12, 2012–13, 2013–14). Treatments were green manure species [red clover (T. pratense L.) and white clover (T. repens L.)] undersown into winter wheat in March and green manure mowing regime (one late summer mowing or no mowing). We measured wheat productivity and grain protein at wheat harvest, and clover and weed above-ground biomass as dry matter (DM) at wheat harvest, 35 days after wheat harvest, in October and in April before clover termination. Winter wheat grain yields and grain protein were not affected by undersown clovers. DM was higher for red than for white clover at most sampling times. Red clover produced between 0.4 and 5.5 Mg ha−1 in the fall and 0.4–5.2 Mg ha−1 in the spring. White clover produced between 0.1 and 2.5 Mg ha−1 in the fall and 0.2–3.1 Mg ha−1 in the spring. Weed DM was lower under red clover than under white clover at most sampling times. In the spring, weed DM ranged from 0.0 to 0.6 Mg ha−1 under red clover and from 0.0 to 3.1 Mg ha−1 under white clover. Mowing did not consistently affect clover or weed DM. For organic growers in eastern Nebraska, red clover undersown into winter wheat can be a productive green manure with good weed suppression potential.

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Response of Wetland Taro Yield and Weeds to Preplant Establishment of Azolla in Hawaii

HortScience ◽

10.21273/hortsci.30.4.912f ◽

1995 ◽

Vol 30 (4) ◽

pp. 912F-912

Author(s):

Joseph DeFrank

Keyword(s):

Phosphoric Acid ◽

Green Manure ◽

Dry Weight ◽

Weed Suppression ◽

Symbiotic Relationship ◽

Seeding Rate ◽

Azolla Filiculoides ◽

Blue Green Algae ◽

Nursery Pond ◽

Flooded Rice

Azolla (Azolla filiculoides) is a floating fern that maintains a symbiotic relationship with an N-fixing blue-green algae. In many parts of Asia, azolla is used as a green manure in flooded rice cultivation. Taro (Colocasia esculenta) grown under flooded conditions is used to produce a traditional Hawaiian staple, poi. Azolla has been present in Hawaii for many years, but is not used in a controlled way for either nutrient augmentation of production sites or weed suppression. In this experiment, azolla was removed from a stream on the island of Kauai and multiplied in a nursery pond. Phosphoric acid was added to the nursery pond as a nutrient (P = 5 ppm) at 5-day intervals to accelerate azolla growth. Azolla was moved from the nursery pond and added to taro production plots at a seeding rate of 488 kg·m–2. Phosphoric acid was used in production plots to hasten coverage of the water surface by azolla. Ten days after azolla inoculation, production plots were covered and taro seed pieces were planted. Weed dry weights from conventional and azolla covered plots were recorded 91 days after taro planting. Taro corms were harvested 315 days after planting. Weed dry weight in azolla plots was 86% less than conventional plots. Azolla delayed taro maturity, causing a 41% reduction in marketable corm yield.

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Optimal seeding rate for organic production of field pea in the northern Great Plains

Canadian Journal of Plant Science ◽

10.4141/cjps08113 ◽

2009 ◽

Vol 89 (3) ◽

pp. 455-464 ◽

Cited By ~ 10

Author(s):

J. M. Baird ◽

F. L. Walley ◽

S. J. Shirtliffe

Keyword(s):

Great Plains ◽

Green Manure ◽

Inorganic Nitrogen ◽

Block Design ◽

Organic Production ◽

Weed Suppression ◽

Field Pea ◽

Northern Great Plains ◽

Seeding Rate ◽

Post Harvest

Seeding rates have not been established for organic production of field pea in the northern Great Plains and producers must rely upon a recommended target stand of 88 plants m-2 for conventional production of this crop. This seeding rate may not be suitable as the two systems differ in the use of inputs and in pest management. The objective of this study was to determine an optimal seeding rate for organic production of field pea considering a number of agronomic factors and profitability. Field sites were established using a randomized complete block design with increasing seeding rates, summerfallow and green manure treatments. Seed yield increased up to 1725 kg ha-1 with increasing seeding rate. Weed biomass decreased with increasing seeding rate by up to 68%. Post-harvest soil phosphorus levels and soil water storage did not change consistently between treatments. Post-harvest soil inorganic nitrogen (N), however, was higher for the summerfallow and green manure treatments than for the seeding rate treatments. Field pea reached a maximum economic return at a seeding rate of 200 seeds m-2 and an actual plant density of 120 plants m-2. Organic farmers should increase the seeding rate of field pea to increase returns and provide better weed suppression. Key words: Pea (field), organic, seeding rate, weed suppression, profit, soil N

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Sesbania rostrata as a green manure for lowland rice: Growth, N2 fixation,Azorhizobium sp. inoculation, and effects on succeeding crop yields and nitrogen balance

Biology and Fertility of Soils ◽

10.1007/bf00709647 ◽

1989 ◽

Vol 7 (3) ◽

pp. 191-197 ◽

Cited By ~ 29

Author(s):

J. K. Ladha ◽

S. Miyan ◽

M. Garcia

Keyword(s):

Nitrogen Balance ◽

N2 Fixation ◽

Green Manure ◽

Crop Yields ◽

Lowland Rice ◽

Sesbania Rostrata ◽

Rice Growth

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Weed suppression in Vigna unguiculata with a spring-seeded brassicaceae green manure

Crop Protection ◽

10.1016/j.cropro.2004.09.015 ◽

2005 ◽

Vol 24 (5) ◽

pp. 441-447 ◽

Cited By ~ 28

Author(s):

Jason K. Norsworthy ◽

Lynn Brandenberger ◽

Nilda R. Burgos ◽

Melissa Riley

Keyword(s):

Vigna Unguiculata ◽

Green Manure ◽

Weed Suppression

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Weed supression by smother crops and selective herbicides

Scientia Agricola ◽

10.1590/s0103-90162004000100004 ◽

2004 ◽

Vol 61 (1) ◽

pp. 21-26 ◽

Cited By ~ 7

Author(s):

Francisco José Severino ◽

Pedro Jacob Christoffoleti

Keyword(s):

Field Experiment ◽

Weed Management ◽

Green Manure ◽

Residual Effect ◽

Cropping System ◽

Pigeon Pea ◽

Weed Suppression ◽

Integrated Weed Management ◽

Weed Species ◽

Arachis Pintoi

Using a smother crop is thought to suppress weed density and to add other beneficial effects in sustainable agricultural systems. Weed suppression ought to be considered an essential component of integrated weed management. However, very little is known about the effects of green manure plants on weeds. This study evaluated the influence of three green manure species on weed suppression and selectivity of herbicides. A field experiment was designed to determine the effect of the green manure species Crotalaria juncea, Arachis pintoi and pigeon pea on the weeds Brachiaria decumbens, guineagrass and hairy beggarticks, and on the natural weed infestation in the inter rows area of an avocado orchard. The weed species were suppressed differently by each green manure species. Soil samples collected from the field experiment presented a residual effect, of at least 30 d, in suppressing weed seed bank recruitment; this residual effect was caused by the residues of the green manure present in the soil. When the green manure was incorporated into the top 5 cm of soil or left on the surface, in a greenhouse experiment, the emergence of weed seeds was significantly inhibited, depending on the species, and on the amount and depth of green manure incorporation. Greenhouse experiments indicate that pre-emergence herbicides cause lower phytotoxicity than post-emergence Arachis pintoi. Smother crops using green manure species, when well established in an area, provide additional weed control to the cropping system and are effective and valuable tools in integrated weed management.

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