Why Use Cover Crops Better soil structure Organic

Why Use Cover Crops? • Better soil structure & Organic Matter – Increased water holding capacity – Better soil aeration – Rooting action • Increased nutrient availability – Nitrogen production • Soil erosion control • Increased soil microbial activity • Soil borne pest control – Soil microbial activty • Weed control

Winter Cover Crop • Most adapted to Southern US – Planted late summer or fall • Legume-nitrogen fixing • Often used in mixes – Legumes – Grains-oats, rye, & wheat

Summer Cover Crop • Summer Legumes to add Nitrogen – Cowpeas, soybeans, annual sweetclover, sesbania. crotalaria, velvet beans • Nonlegumes for weed suppression and biomass – Millet, sorghum-sudan grass, buckwheat

Organic Matter • Organic matter important in soil quality • OM breaks down to from gums, waxes, and resins. – Hold soil together to form aggregates – Results in higher water infiltration and easier tilling. • OM eventually breaks down to form humus. Long lasting organic component of soil. • Annual legume green manures adds little to humus in soil.

Rooting Action • Deep rooting of some cover crops aid in soil aeration • Can be used “deep plow” soil. • As deep roots decompose they leave channels for water and air to penetrate.

Rooting Depth Safflower 10 -12 ft Red Clover, Lupine, radish, Turnips 5 -7 Common Vetch, Mustard 3 -5 White Clover, Hairy Vetch 1 -3

Average Biomass Production Cover Crop Sweet Clover Yield (dry matter) 1. 75 Tons/A Hairy vetch 1. 75 Mustards 4. . 25 Sorghum-sudan grass 2. 5 Green manures can add the equivalent of 9 -13 tons of compost or more

Nutrients • Nitrogen production – Legumes can add from 40 to 200 lbs N/A – Environmental conditions need to be correct to get the highest N production, p. H, other nutrients, stand, etc. • 40 -60% of nitrogen produced will be available the first year, less for the following crops. • Can calculate how much N produced by cover crop

Average Nitrogen Production Cover Crop Nitrogen Yield lbs/A Sweet Clover 120 Hairy Vetch 110 Legume Mix @ KAC 120

Nutrient Recycling • Cover crops recycle nutrients already in soil. – Some crops are known for accumulating nutrients from the soil, N, P, K, Ca, Mg, S, and others – eg Buckwheat, lupine, & sweet clover can accumulate P. • Deep soil mining – Pulling nutrients from deep in the soil to surface to be used again – Prevent nitrate leaching

Erosion Control • Wind erosion – Many cover crops can be used for wind erosion • Water erosion

Dust Suppression 30 days after incorporation

Soil Microbial Activity • OM provides the food source for soil microbes. • The greater number of microbes and diversity, the more healthy the soil • Soil borne pathogens do not compete well with other soil microbes. • Predation, parasitism, exclusion, keep plant pathogens at low levels

The Use of Mustards as a Green Manure Cover Crop • Bio-fumigation Effect– fumigation with chemicals released from plant material. • May suppress soil borne pests/pathogens • Pythium (violae and sulcatum) sp. – Cavity spot • Nematodes – root knot nematode • Weeds

How it Works Glucosinolate + = ITC’s isothiocyanate Enzymes Produced by Mustard Plant R e l Biofumigant

Crops Use of Mustard Cover Grow as much biomass as possible. – Flail chop at 80% bloom • • • Flail chop to rupture plant tissue before seed set. High glucosinolates. Need maximum production of both High biomass. Incorporate with disc. Apply water after incorporation – ½ inch water.

Mustard Varieties Tested • Pacific Gold - Brassica juncea - Brown mustard • ISCI 20 - Brassica juncea - Brown Mustard • Absolute – Sinapis alba – White Mustard • Blend 119 – B. juncea & S. alba Brown/White

Mustard Trials • Trials conducted in Antelope Valley, Cuyama Valley, and Kern County. • Planted to either carrots or potatoes after mustard green manure. • Measurements made on: – Mustard yields, crop yields (carrot or potato), cavity spot control, nematode control, and changes to soil microbiology.

Water Infiltration-Carrots

2003 Mustard Trial

Yield for 1/100 of Harvested Acre Fallow Pacific Gold ICHI 20 Absolute Blend 119 Fallow/Metam P= LSD, 0. 05 %CV Total Yield (lbs) 491. 0 491. 3 491. 2 483. 7 510. 7 512. 0 0. 6787 NS 5. 95 Sum of Squares for Select Contrast Fallow vs all 154. 7 Fallow vs Blend 119 775. 982 Fallow vs Fallow/Metam 885. 573 Fallow/Metam vs Blend 119 3. 618 Fallow/Metam vs all mustards 1012. 464 *contrast are significant at P=0. 05 Marketable Yield (lbs) 394. 1 A 389. 1 A 414. 3 AB 396. 7 A 440. 3 B 434. 7 B 0. 0369 36. 953 5. 96 1465. 105 4278. 125 * 3300. 782* 63. 281 1932. 578

2004 Potato Trial

2005 Potato Trial Carrots Mustard Fallow/Wheat Mustard Potatoes Fall 2003 Spring 2004 Spring/Summer 2004 Fall 2004 Winter 2005

Conclusions • Mustards can be grown successfully in either fall or spring with significant amount of biomass. • Soil microbiology can be significantly changed. • Water infiltration rate are increased. • Yields increased compared to fallow control and equal to metam controls. • Does not control Sclerotium roflsii. • Appears to reduce plant parasitic nematodes.

BUT. . .

Problem: the majority of brassica species are hosts to root-knot nematodes (Meloidogyne). Solutions 1. Grow Brassicas during cool season 2. Remove Brassicas before eggs are produced 2. Use resistant Brassicas

Antoon Ploeg’s Experiment: To select Brassica vars that are poor/non-hosts for Meloidogyne To test the effects of Brassica vars. on growth, yield and nematode infection of following tomato crop.

First experiment (in pots in greenhouse): compare the multiplication of M. incognita on cruciferous varieties. • • 32 varieties. Soil with M. incognita, 3 plants/pot. Count nr nematodes after 6 wks, (tomato control). Results: large differences, some are very good hosts (like tomato), others almost resistant.

Number M. incognita J 2 after 6 wks in pots, under different cruciferous vars. Plant species Common Name Variety Nr J 2 Solanum lycopersicum tomato UC 82 4, 271 a 1 Brassica juncea Indian mustard Pacific Gold 3, 226 ab Brassica rapa field mustard/turnip Br 02206 2, 423 abc Brassica juncea Indian mustard ISCI 99 2, 422 abc Brassica juncea Indian mustard Nemfix 2, 134 abc Brassica rapa field mustard/turnip Samson 1, 369 bcd Sinapsis alba white mustard Condor 1, 234 bcd Brassica rapa field mustard/turnip Rondo 1, 084 bcd Brassica napus rutabaga/rape Humus 1, 079 bcde Brassica rapa field mustard/turnip Br 02205 995 cdef Sinapsis alba white mustard Accent 648 defg Sinapsis alba white mustard Absolut 566 defgh Raphanus sativus fodder radish Doublet 556 defgh Brassica napus rutabaga/rape Greenland 554 defgh Brassica carinata Ethiopian/Abyssinian mustard Bc 007 554 defgh Brassica napus rutabaga/rape Winfred 546 defgh Sinapsis alba white mustard Maxi 505 efghij Sinpasis alba white mustard Achilles 502 defgh Sinapsis alba white mustard Ida Gold 487 defgh Sinapsis alba white mustard Santa Fe 480 defghi Rapahanus sativus fodder radish Final 468 fghij Sorghum bicolor x sudanense sorghum-sudangrass Toshan’s 372 efghij Sinapsis alba white mustard Abraham 351 ghij Raphanus sativus fodder radish Adios 284 ghijk Raphanus sativus fodder radish Rs 05415 277 ghijk Raphanus sativus conv. oleiformis fodder radish Defender 267 hijk Eruca sativa arugula/roquette Nemat 257 hijk Raphanus sativus conv. oleiformis fodder radish Colonel 201 ijk Raphanus sativus conv. oleiformis fodder radish Adagio 190 kl Raphanus sativus conv. oleiformis fodder radish Comet 141 jk Rapahanus sativus fodder radish Terra. Nova 63 l Brassica oleracea broccoli Liberty 9 m Raphanus sativus conv. oleiformis fodder radish Boss 7 m 1 different letters indicate significant differences at 95% confidence level. Statistics done on log(x+1)-transformed data, non-transformed data shown.

2 nd Experiment: test a selection of varieties in the field, and effects on a following tomato crop. • 3 ft diameter concrete tubes, sandy soil with M. incognita • • Varieties seeded in February 2007 Cut, chipped, and incorporated in May 2007 • tomatoes transplanted June 2007 • Nematodes counted, gall index, and biomass (cruciferous), yield, nematode infestation, galling of tomatoes.

Host Status : Relation between results from GH and micro-plot exps 20 Order vars. Microplots 15 10 5 0 0 5 10 Order vars GH exp 15 20

Abraham Adagio Adios Boss Br 02206 Colonel Comet Defender Greenland Achilles Carrot ISCI 9 Liberty Nemat Nemfix Pacific Gold Rs 054 Samson Terra. Nova kg Biomass production of the cruciferous varieties in microplots. 5 4 3 2 1 0

Abraham Adagio Adios Boss Br 02206 Colonel Comet Defender Greenland Achilles Carrot ISCI 9 Liberty Nemat Nemfix Pacific Gold Rs 054 Samson Terra. Nova Galling on roots of cruciferous varieties in Micro-plots. 6 5 4 3 2 1 0

Basamid Fallow Carrot Abraham Achilles Adagio Adios Boss Br 02206 Colonel Comet Defender Greenland ISCI 9 Liberty Nemat Nemfix Pacific Gold Rs 054 Samson Terra. Nova Galling on tomato roots after different cruciferous varieties. 10 9 8 7 6 5 4 3 2 1 0

Basamid Fallow Carrot Abraham Achilles Adagio Adios Boss Br 02206 Colonel Comet Defender Greenland ISCI 9 Liberty Nemat Nemfix Pacific Gold Rs 054 Samson Terra. Nova Kg tomates Tomato yields after different cruciferous varieties. 5 4 3 2 1 0

Relation between tomato yield and RKN numbers in soil after biofumigation. Tomato yield (g) 4000 3500 3000 R 2=0. 66, p≤ 0. 001 2500 2000 1500 1000 500 0 0. 5 1. 0 1. 5 log. Pf. Biofum 2. 0 2. 5

Conclusions: • There are large differences in host status for M. incognita between different cruciferous varieties • In general, varieties of Raphanus sativus are the more resistant varieties. • To predict the host status of a cruciferous variety for RKN, GH pot trials can be employed. • The host status of a variety appears more important than its biofumigant effect in RKN control • The nr of nematodes in soil after biofumigation, prior to tomato transplanting was strongly inversely correlated with the tomato yield. • A few cruciferous varieties resulted in tomato yields similar to a Basamid treatment and increased yields compared to fallow about 3 -fold.

Other Cover Crops with Known Nematicidal Properties

Sun Hemp • Tropical erect, branching, annual legume • Green manure crop used to add nitrogen and organic matter • Can reduces root knot nematodes • Provides weed suppression • Must be plowed down before reaching full-bloom stage or becomes too fibrous • ‘Tropic Sun’ cultivar is non-toxic to poultry and livestock

Sudan-Sorghum Hybrids • • • Summer Cover Crop Can be mixed with some legume for other benefits Biomass matter source (Dry Matter: 8, 000 -10, 000 lbs/ac/yr) • Weed suppression • Nematode and disease suppression • Subsoil loosener • Forage • Insectary plant

Cow Pea Vigna unguiculata • Nitrogen source (100 -150 lb. N/ac) • Biomass/organic matter source (Dry Matter: 2, 500 -4, 500 lbs/ac/yr) • Weed suppression • Insectary plant • Companion crop in orchards, vineyards, corn • Drought tolerant • Food, seed, forage, or hay crop

Sesame • Effective rotation crop to control Meloidogyne arenaria and Meloidogyne incognita • Sesame rotation is not effective however, for Meloidogyne javanica

Marigold Tagetes spp • In greenhouse experiments marigold varieties were identified with high efficacy in nematode control. • Subsequent field tests showed that selected species lowered nematode populations and increased yields similar to soil fum. Igation

Variety Selection Can be Crucial • Need to make sure that cover crop variety selected for nematode control is not itself a host • Can use planting dates to avoid some of the problems of variety selection

Alternative Nematicides • Like the use of cover crops, many are old remedies • Many are biological or organic based • They work to a degree, but not as effective as soil fumigants • Likely have a fit as fumigants become more restricted in use

Mustard Meal By-product of bio-diesel production. High in glucosinolates. 6% nitrogen by weight.

Bio-Pesticide Herbicide Insecticide Nematicide

Materials in Evaluation Now • Sesame Oil- applied as a drench • Appears to have some efficacy • Dragonfire CCP • Na. Ex. Corporation/Poulenge r USA

Materials in Evaluation Now • Nemagard – Pelletized sesame stalk – Do not see any efficacy at this time

Materials in Evaluation Now • Shrimp/Crab Meal • Nematode egg cases and exoskeleton made of Chitin. • Adding chitin to soil builds up microbes that produce chitanse to break down chitin • Chitinase in the soil destroys nematode eggs • May be working somewhat

Materials in Evaluation Now • Neemcake • Seed meal left behind after crushing neemseed for neem oil production • At this time does not appear to be working

Materials in Evaluation Now • Ne-Plex-Terra Biotics • Bacillus chitonosporus • Soil borne bacteria that produces chitinase • Does not appear to be working at this time

Insecticides that have Nematicidal Properties • Movemento-Bayer Crop. Science • Aphidcide that moves down through phloem • Very systemic • Appears to be an excellent nematicide in our trials. • Lipid Biosynthesis Inhibitor (LBI).

Movento 5 oz (4 apps @ 14 day interval)

Untreated

Abamectin Seed Treatment • Root length and plant height were significantly increased • Seed coating with abamectin delays rootknot nematode damage • Avicta – Syngenta Crop Science • Produced by Streptomyces avermiltilis a bacteria

Abamectin Seed Treatment

Conclusions Sustainable agriculture is no longer a buzz word. – means an integrated system of plant and animal production practices having a site-specific application that will over the longterm: • Satisfy human food and fiber needs. • Enhance environmental quality and the natural resource base upon which the agriculture economy depends. • Make the most efficient use of nonrenewable resources and on-farm resources and integrate, where appropriate, natural biological cycles and controls. • Sustain the economic viability of farm operations. • Enhance the quality of life for farmers and society as a whole. • Modern nematode control will require a more integrated approach as fumigants become more restricted.

Conclusions • Cover crops and green manures will play a role in increasing soil health. • Selection of cover crops and green manures will depend of what the needs are. • “Old” nematode remedies need to be reevaluated for modern ag systems • New softer nematicidal materials are far and few but are appearing.