Vetch Plots Research Articles

Effect of Different Cover Crops on Suppression of the Weed Oxalis pes-caprae L., Soil Nutrient Availability, and the Performance of Table Olive Trees ‘Kalamon’ cv. in Crete, Greece

Winter cover crops are used in organic olive production to increase N-supply and yields, and to reduce weed competition. However, there is limited information on the effect of different cover crops on weed suppression, soil fertility and productivity of organic olive orchards. Here, we compared the relative effect of four contrasting cover crops established from (i) untreated vetch seed, (ii) vetch seed inoculated with a commercial Rhizobium seed inoculum, (iii) an untreated vetch/barley/pea seed mixture and (iv) untreated seed of Medicago polymorpha L. (a native legume species which establishes naturally in olive orchards in Crete) in a 35-year-old experimental table olive orchard. The use of a vetch/barley/pea mixture resulted in the greatest suppression of the dominant weed species Oxalis pes-caprae. Rhizobium inoculation of vetch seed resulted in significantly lower vetch establishment and significantly higher Oxalis suppression but had no significant effect on the root nodulation of vetch plants. There was no significant difference in fruit yield between cover crop treatments, but the fruit weight was significantly higher when cover crops were established from un-treated vetch seeds and the vetch/barley/pea seed mixture compared with the cover crops based on inoculated vetch or Medicago seed. However, although Medicago establishment was very low (<10 plants/m2), fruit yields were numerically 20% higher in the Medicago plots. These findings suggests that, overall, legume cover crops had no effect on fruit yields. This conclusion is supported by the results of the olive leaf analyses which detected no significant differences in nitrogen and other mineral macro- and micronutrient concentration between treatments, except for B (highest in olive leaves from Medicago and lowest in untreated vetch plots) and Mo (highest in olive leaves from Medicago and lowest in vetch/barley/pea mixture plots). Overall, our results suggest that the current recommendation to establish legume-based cover crops in organic olive orchards every year, may need to be revised and that establishing cover crops every 2–4 years may reduce costs without affecting olive fruit yields.

Soil Enzyme Activities Affecting by Different Tillage Systems and Cover Crops Following Corn Cultivation

Cover crops and minimum tillage or zero- tillage practices are the soil conservation management practices. These practices improve or sustain soil properties especially soil organic matter. In the study, we investigated the effects of cover crops and tillage practices on soil urease, alkaline phosphatase and catalase activities at different soil depths following corn. The corn was planted in May, and the cover crops (common vetch, fodder beet, mix of common vetch and fodder beet) were planted in late summer under minimum and conventional tillage. Soil samples were collected at 0-10, 10-20 and 20-30 cm soil depths in 2018. With respect to results of the study, cover crops affected all the enzyme activities while tillage systems affected urease and catalase activities in soil. The highest urease (9.91 and 7.48 µg g N soil-1 h-1), alkaline phosphatase (99.29 and 84.61 µg g p-nitrophenol soil-1 h-1) and catalase (58.73 and 64.82 ml O2 3 min-1 g soil-1) activities were in common vetch plots in minimum and conventional tilled plots and all the enzyme activities were decreased with increasing soil depth. The results suggest that cover crops and minimum tillage practices increase soil enzyme activities.

​Effect of Legume and Cereal Mulches on Weed Dynamics and Potato Yield

Background: Non-chemical management methods, including cover crops, has an essential role in diminishing weed infestations and reducing the use of herbicides. Methods: To evaluate the suppressive effects of four cover crop options on weed populations, a field experiment was conducted in factorial randomized bock design with three replications at Ardabil Agricultural and Natural Resources Research Station, Ardabil, Iran, in 2016. The treatments consisted of legumes and cereal cover crop as one factor (Control, Rye, Common vetch, Grass pea and Hungarian vetch) and crop management strategies as a second factor [forage use (FU) and land cover use (LCU)]. Result: Grass pea sown as fodder use strategy recorded the highest fresh and dry weight of weeds significantly. The greatest potato yield production was observed in Rye and Hungarian vetch plots, approximately 5000 kg ha-1 in both FU and land LCU strategies. Generally, it seems that Rye and Hungarian vetch could be acceptable options to use in potato production as cover crops.

Winter cover crops effects on soil properties and sweet corn yield in semi‐arid irrigated systems

AbstractWinter cover crops (WCCs) can bolster agroecosystem services, including improving soil and crop yields. However, information is lacking about WCCs in irrigated crops in the semiarid climates of the southwestern United States. We chose three WCC species for their ecological attributes: hairy vetch (Vicia villosa, nitrogen fixation), rye (Secale cereale, nutrient sequestration; allelopathy), and mustard (Brassica juncea, biofumigant). Crops were planted in either monoculture or 2‐ and 3‐way combinations to evaluate agroecosystem services. Sweet corn (Zea mays L.) was planted approximately 2 wk after WCC termination. Neither monocultures nor mixtures consistently produced the most biomass, as WCC biomass production differed between site and year. The highest yielding cover crop was vetch (4302 kg ha−1) followed by mustard–vetch (3528 kg ha−1) and rye–vetch (3130 kg ha−1), all within the same site year, and rye (3016 kg ha−1) in another site year. Cover crops generally increased mean weight diameter of soil aggregates (a measure of dry soil aggregation) over time, with values nearly doubling in mustard–vetch and mustard–rye–vetch plots at one site. Wet aggregate stability increased by as much as 18% in mustard and 27% in mustard–vetch plots. Fertilizer requirements decreased compared to fallow plots in the second year in all WCC plots except for rye at one site, and vetch increased sweet corn yield compared to dry fallow plots in 1 yr by an average of 43.1%. These results demonstrate that WCCs can have positive effects on dry aggregate stability and potentially cash crop yield in irrigated, semiarid agroecosystems.

Effect of Legume Cover Crops and Nitrogen Fertilization Rates on Yield and Nitrogen Use Efficiency of Waxy Corn (Zea mays L.) in No-Tillage System

The adoption of legume cover crops in no-tillage system can contribute to improve soil fertility by providing several benefits, including reduction in soil erosion, suppression of weed growth and N supply to subsequent crops. We conducted a field study to investigate the effect of cover crops and nitrogen fertilization rates on yield and nitrogen use efficiency of waxy corn (Zea mays L.) in no-tillage upland field. Two legume cover crops, hairy vetch (Vicia villosa Roth) and crimson clover (Trifolium incarnuturn L.) were mechanically terminated with roller in early June. For each cover crop treatment, nitrogen (N) fertilizer was applied at three different rates (145, 72.5 and 0 kg N ha-1 ). The growth and yield characteristics of corn were significantly affected by the N fertilization rates in crimson clover plots, which suggest N mineralization from the cover crop residue was not sufficient. In contrast, N fertilization rates had no significant effect on growth and yield of corn in hairy vetch plots, indicating that the amount of N released from the cover crop is large enough to meet most of the N requirement of corn. However, the application of N fertilizer in hairy vetch cover plots resulted in slight increase of crop yield, though not statically significant, and high levels of N concentration in corn plant tissue possibly due to luxury consumption of N. Organic residues on the soil surface in hairy vetch cover plots had substantial amounts of N after harvest, ranging from 100 to 116 kg N ha -1 , which is presumably retained during winter season and released by microbial mineralization in subsequent year. The highest nitrogen yield efficiency was achieved in the plot with hairy vetch cover and no N fertilizer application, followed by the plot with hairy vetch cover and 72.5 kg N ha -1 fertilization rate. In conclusion, hairy vetch showed better performance in corn productivity as compared with crimson clover. In addition, it was concluded that the application of N fertilizer between 0 and 72.5 kg N ha -1 in combination with hairy vetch cover crop might be most efficient for corn yield under no-tillage system with climatic and soil characteristics similar to those of the experimental site.

Effects of Cover Crop Species and Season on Population Dynamics of Escherichia coli and Listeria innocua in Soil.

Cover crops provide several ecosystem services, but their impact on enteric bacterial survival remains unexplored. The influence of cover cropping on foodborne pathogen indicator bacteria was assessed in five cover crop/green manure systems: cereal rye, hairy vetch, crimson clover, hairy vetch-rye and crimson clover-rye mixtures, and bare ground. Cover crop plots were inoculated with Escherichia coli and Listeria innocua in the fall of 2013 and 2014 and tilled into the soil in the spring to form green manure. Soil samples were collected and the bacteria enumerated. Time was a factor for all bacterial populations studied in all fields (P < 0.001). E. coli levels declined when soil temperatures dipped to <5°C and were detected only sporadically the following spring. L. innocua diminished somewhat but persisted, independently of season. In an organic field, the cover crop was a factor for E. coli in year 1 (P = 0.004) and for L. innocua in year 2 (P = 0.011). In year 1, E. coli levels were highest in the rye and hairy vetch-rye plots. In year 2, L. innocua levels were higher in hairy vetch-rye (P = 0.01) and hairy vetch (P = 0.03) plots than in the rye plot. Bacterial populations grew (P < 0.05) or remained the same 4 weeks after green manure incorporation, although initial reductions in L. innocua numbers were observed after tilling (P < 0.05). Green manure type was a factor only for L. innocua abundance in a transitional field (P < 0.05). Overall, the impacts of cover crops/green manures on bacterial population dynamics in soil varied, being influenced by bacterial species, time from inoculation, soil temperature, rainfall, and tillage; this reveals the need for long-term studies.

Effects of two legume crops, for organic green manure, on weed flora, under mediterranean conditions: Competitive ability of five winter season weed species

Field experiments were conducted to determine the effects of vetch (Vicia sativa c.vlexander) and red clover (Trifolium pratense c.v Nemaro) on weed flora. The design of the experiment was randomized complete block with 4 replicates and 3 treatments (a: vetch crop, b: red clover crop and c: control (fallow)). Both legume crops suppressed weed biomass. The lowest number and dry weight of weeds was found in vetch plots. The highest height of weeds was found in control plots. Moreover, the highest multiplied dominance ratio (MDR) of weeds was found in the control plot. Vetch was the most competitive legume crop. The number of shoots per plant and dry weight were considered suitable attributes for weed suppression, although competitiveness is a relative rather an absolute characteristic. In addition, red clover is considered a poor competitor because of lack of seedling vigour and slow establishment. Statistically significant negative correlation between the fraction of photosynthetically active radiation (PAR) intercepted by the canopy, weed density and weed biomass was observed. The MDR of weeds (Lamium aplexicaule, Papaver rhoeas, Sinapis arvensis, Chamomilla recutita and Phalaris minor) had a good correlation with dry weight of weeds. Analysis of MDR demonstrated that L. aplexicaule and C.recutita are poor competitors because of small leaves and low height. Final, S. arvensis and P. minor were the most competitive weeds.

First Report of Bacterial Blight Caused by Pseudomonas syringae pv. syringae on Common Vetch in Spain.

Common vetch (Vicia sativa L.) is an important legume crop used for livestock feed in the Mediterranean Area. This crop has an important role for sustainable agriculture in dryland rotations in Spain, where the Castilla y León Region is the major production area. During the springs of 2007 and 2008, necrotic lesions on stems, leaves, and flowers were observed in five different common vetch plots around Medina de Rioseco (Castilla y León). Four of the plots were sown with cv. Buza. No information was available about the cultivar in the fifth plot. In many cases, lesions had expanded into the stems causing complete wilting. Disease incidence was estimated at approximately 20%. Two symptomatic plants per plot were sampled. One section per plant was individually surface disinfested in 0.5% NaOCl for 1 min, followed by three washes in sterile water. Macerates were plated in King's B medium (KB) agar (24°C for 48 h) (2). Colonies from all isolations on KB agar were pale yellow and blue-green fluorescent under UV light, as typical of fluorescent Pseudomonas spp. (2). Ten isolates (one per section) were characterized. These were identified as Pseudomonas syringae by the LOPAT scheme (2) and Hugh-Leifson reaction and all utilized erythritol, l-lactate, and dl-homoserine, but not l(+)-tartrate, as carbon sources. They were positive for aesculin and gelatine hydrolysis. The 10 isolates caused severe necrotic lesions when they were puncture inoculated (108 CFU/ml suspension, 50 μl per wound, and two replicates) on immature lemon fruits (Citrus × limon, cv. Primofioro), bean pods (Phaseolus vulgaris L., cv. Ancha Lisa), and pea pods (Pisum sativum L., cv. Ucero). PCR amplification of a 752-bp syrB fragment (3) was positive for all isolates. On the basis of these tests, the 10 isolates were identified as P. syringae pv. syringae (2). Subsequently, each isolate was inoculated into two sets of 10 plants of V. sativa cv. Buza by injecting 200 μl of a bacterial suspension (108 CFU/ml) into the stem (2); 10 plants were injected with sterile water as controls. Ten days after inoculation, necrotic symptoms were observed on all plants, and 1 week later, all plants were completely wilted and dead. These symptoms were similar to those observed in the field. Control plants remained symptomless. Isolations were made from two inoculated plants per each original isolate, and all reisolates were identical to the original isolates in the above biochemical tests and PCR of the syrB gene. P. syringae pv. syringae reference strains, CFBP1768 and CFBP1769 (Collection Française de Bactéries Phytopathogènes), gave the same results in all biochemical, pathogenicity, and PCR tests. To our knowledge, this is the first report of bacterial blight caused by this pathogen on vetch in Spain. This pathogen had been previously identified in this crop in France (4) and in V. villosa (a closely related species) in the United States (1). Therefore, to prevent the spread of this pathogen, research on efficient preventive and control measures is needed.

Weed suppression in organic pepper ( Capsicum annuum L.) with winter cover crops

Weed control is a major constraint for organic production around the world. Field studies were conducted in pepper ( Capsicum annuum L.) from 2004 to 2006 at the Black Sea Agricultural Research Institute experimental field in Turkey to determine the weed suppressive effects of winter cover crops. Treatments consisted of ryegrass ( Lolium multiflorum L.), oat ( Avena sativa L.), rye ( Secale cereale L.), wheat ( Triticum aestivum L.), gelemen clover ( Trifolium meneghinianum Clem.), Egyptian clover ( Trifolium alexsandrinum L.), common vetch ( Vicia sativa L.), hairy vetch ( Vicia villosa Roth.) and a bare fallow with no cover crop. Weed density and total weed dry biomass were assessed at 14, 28, and 56 days after incorporation to quantify effects of cover crops during a subsequent pepper crop. Cover crop establishment was similar in both growing seasons and individual species produced in the range of 1800–3500 kg/ha biomass. Ryegrass produced the greatest biomass compared with other species. Weed dry biomass production just before cover crop incorporation varied with year and cover crop species. Hairy vetch, ryegrass, oat and common vetch were the most competitive cover crops based on total weed dry biomass. Hairy vetch was the most promising cover crop and reduced weed density by 73% and 70% at 28 and 56 DAI, respectively. Pepper yields were higher following all cover crops except Egyptian clover. The highest yield was obtained from hairy vetch plots in both years. This research indicates that cover crops such as hairy vetch, ryegrass, oat and common vetch could be used in integrated weed management programs to reduce weed infestation in organic pepper.

Winter Cover Crops and Vinegar for Early-Season Weed Control in Sustainable Cotton

ABSTRACT Weeds may be suppressed by winter cover crops and the use of organic herbicides such as vinegar. Black oat (Avena strigosa) and hairy vetch (Vicia villosa) winter cover crops were planted for 2 years as part of a sustainable production system for cotton in the Lower Rio Grande Valley of Texas, and were till-killed each spring prior to cotton planting. Palmer amaranth (Amaranthus palme ri), common purslane (Portulaca oleracea), and sunflower (Helianthus annuus) were frequently-encountered winter and spring weeds. Both cover crops controlled winter weeds as well as did winter tillage without cover. Black oats plots had 8% and 17% more total winter weed cover than no-cover and hairy vetch plots, respectively. Seven weeks after cotton planting, cotton cover was 10% to 15% less in former winter hairy vetch and no-cover sustainable plots than in former black oats plots, but cotton height did not vary by winter cover crop. Total spring weed, pigweed, and purslane cover did not vary between former hairy vetch, black oats, and no-cover plots. All sustainable plots had higher spring weed cover than did conventional plots maintained with cultivation and synthetic herbicides. Breakdowns in the sustainable spring weed management system (withholding of spring cultivation) or insect pest management system (failure of alfalfa strips) led to increases of 60% or more in weed cover in sustainable plots. Cotton lint yield (kg/ha) did not differ between sustainable and conventional weed management systems. When evaluated as a cover crop and weed management tool, vinegar containing 9% acid (1,550 L/ha) reduced live hairy vetch cover to less than 5% in one of two trials, but was not effective as a burndown herbicide on black oats. Vinegar at this concentration (2,980 L/ha) killed >80% of 30-day-old or younger cotton and sunflower and 10-day-old Palmer amaranth and purslane in field trials, but caused <50% mortality to mature Palmer amaranth and purslane. More dilute vinegar solutions (0.9% to 4.5% acid) caused little or no mortality. Black oats and hairy vetch covers controlled winter but not spring weeds in this production system. With more prolonged use, winter covers could become a key spring weed control component in sustainable cotton production. Vinegar could be useful in controlling young weed seedlings in non-crop areas, or as a follow-up to cultivation.

Strip Tillage Pumpkin Production Using Rye, and Rye/Hairy Vetch Cover Crop

Pumpkin is usually grown on bare ground. Weeds are controlled by pre-emergence herbicides and cultivation early in the season before pumpkin vines cover the ground. The pumpkin fruit lie on bare ground and covered with soil. In pick-your-own pumpkin operation it is impossible to walk on muddy fields to pick pumpkin fruits. Experiment was carried out using three treatments (Control-bare ground, Rye only mulch, and rye/hairy vetch mulch) replicated four times in complete randomized block design with plot sizes of 30 ft (9 m) by 30 ft (9 m). In each plot, two pumpkin rows were planted 8 ft (2.4 m) a part and 2 ft (0.6 m) a part within rows. In rye only, and rye/hairy vetch plots, two 2-ft wide strips 8-ft a part were mowed and rototilled in each plot. Cover crop in between the rows were rolled using a multi-culchler roller, and emergence of eastern black night shade (Solanum phytanthum Dun.), red root pig weed (Amaranthus retroflexus L.), and common lambsquarters (Chenopodium album L.) on cover crop plots between the rows were evaluated 4-10 weeks after transplanting. The effect of cover mulches on pumpkin fruit number, yield, fruit size, and fruit rots were assessed as well. Emergence of red root pigweed, black nightshade, and common lambsquarters was less than 2, 1, and 1/2 seedlings per 12-ft-2 (1-m-2) area respectively. There was no significant difference in marketable fruit number between control and strip tilled plots. Control plots had higher pumpkin fruit weight than rye/hairy vetch plots, and no significant difference between rye only and rye/hairy vetch plots. Control plots had significantly larger fruits and higher fruit rot incidence than strip tilled plots.

Potential of Winter Cover Crops to Increase Abundance ofSolenopsis invicta(Hymenoptera: Formicidae) and Other Arthropods in Sugarcane: Table 1

A 3-yr study was conducted in Louisiana sugarcane field plots to determine the potential of vegetation management and winter cover crops to enhance abundance of the fire ant, Solenopsis invicta Buren, other arthropods, gastropods, and spring sugarcane density. Treatments included pea, clover, and vetch cultivars, a weed-free herbicide treatment, a vetch with herbicide on the row tops; and a mixed weeds treatment arranged in a randomized complete block design. Compared with similar studies conducted during the summer months, spring collections of arthropods in pitfall traps were very low and few differences in arthropod densities occurred. Neither cover crop cultivar nor biomass substantially influenced arthropod density or cane stand density. Slugs (Limacidae) and earwigs (Dermaptera) were most abundant in mixed weed plots. The highest numbers of carabids in 1994 were found in vetch plots, which tended to have higher biomass than other treatments. Soybean oil-soaked bait cards attracted more ants in clover plots than in the plots with vetch plus herbicide. Compared with previous summer studies, we feel that harsher winter weather and other density independent mortality factors during this study period superseded effects of cover crops, vegetation management and quantity of biomass on arthropod densities during the winter. Although positive impacts of winter cover crops were not detected for the variables measured during the study period these data should not be used to suggest that cover crops do not provide agronomic benefit to farmers.

Nitrogen Requirements of Fresh-market Tomatoes on Hairy Vetch and Black Polyethylene Mulch

A 3-year experiment was conducted to determine the optimum fertilizer N requirements of fresh-market tomato (Lycopersicon esculentum Mill.) `Sunbeam' grown on a hairy vetch (Vicia villosa Roth.) or black polyethylene mulch. In 1993 and 1994, four rates of fertilizer N (0, 56, 112, and 168 kg·ha-1) as water-soluble NH4NO3 were applied in 14 equal applications through the trickle irrigation system starting 1 week after planting. Four additional rates (224, 280, 336, and 392 kg·ha-1) were applied in 1995 to assess the plant response to supra-optimal levels of N. Hairy vetch produced 3.3–4.5 t·ha-1 of above-ground biomass and a total N content of 126–169 kg·ha-1 in the above-ground biomass. Leaf N content at 7 weeks after transplanting of tomatoes correlated positively with yield from black polyethylene but did not correlate with yield from the hairy vetch plots where leaf N content was optimal at all N rates. Predicted tomato yields were higher for the hairy vetch than for the black polyethylene treatment at all applied N rates in all years. Tomatoes grown in black polyethylene required N at 130 to 144 kg·ha-1 to achieve yields equivalent to those grown following unfertilized hairy vetch. Tomato yield increased in response to applied N in both mulches in all 3 years; optimum N rates of 89 and 190 kg·ha-1 in hairy vetch and black polyethylene, respectively, were predicted by a linear plateau model, and 124 and 295 kg·ha-1 by a quadratic plateau model. The linear plateau model is recommended because it would allow less N to become available for runoff and leaching.

Effect of Tillage and Cover Crop on Fluometuron Adsorption and Degradation under Controlled Conditions

Fluometuron adsorption and degradation were determined in soil collected at three depths from no-till + no cover, conventional-till + no cover, no-till + vetch cover, and conventional-till + vetch cover in continuous cotton. These combinations of tillage + cover crop + soil depth imparted a range of organic matter and pH to the soil. Soil organic matter and pH ranged from 0.9 to 2.5% and from 4.7 to 6.5, respectively. Fluometuron adsorption was affected by soil depth, tillage, and cover crop. In surface soils (0 to 4 cm), fluometuron adsorption was greater in no-till + vetch plots than in conventional-tilled + no cover plots. Soil adsorption of fluometuron was positively correlated with organic matter content and cation exchange capacity. Fluometuron degradation was not affected by adsorption, and degradation empirically fit a first-order model. Soil organic matter content had no apparent effect on fluometuron degradation rate. Fluometuron degradation was more rapid at soil pH &gt; 6 than at pH ≤ 5, indicating a potential shift in microbial activity or population due to lower soil pH. Fluometuron half-life ranged from 49 to 90 d. These data indicate that tillage and cover crop may affect soil dissipation of fluometuron by altering soil physical and chemical properties that affect fluometuron degrading microorganisms or bioavailability.

Residual Effects of Interseeded Hairy Vetch on Soil Nitrate-Nitrogen Levels

Increased use of winter legume cover crops has renewed interest in legume N mineralization patterns. This study was conducted to monitor the residual effect of a hairy vetch (Vicia villosa Roth) cover crop and fertilizer N on surface soil NO3-N concentration in no-till and conventional-till corn (Zea mays L.) in northeastern Nebraska on a Nora silty clay loam (fine-silty, mixed, mesic Udic Halplustoll). The experimental design was a split-split-split plot with three replicates. Main plots of conventional tillage and no-till were split into 0, 67, and 134 kg N ha−1 with and without hairy vetch. Soil samples were taken from the 0− to 7.5− and 7.5− to 15−cm depths five times during the 1987 growing season and three times in 1988. Inclusion of a hairy vetch cover crop interseeded during the previous growing season increased soil NO3-N concentration in the surface 7.5 cm between 50 and 64 d after corn planting and in the 7.5- to 15-cm soil layer between 50 and 78 d after corn planting during 1987. In 1988 (a dry growing season), hairy vetch did not significantly increase soil NO3-N concentration in the 0- to 7.5-cm soil layer at any sampling time, but did increase soil NO3-N concentration in the 7.5- to 15-cm depth 103 d after planting. This increase in soil NO3-N concentration occurred in hairy vetch plots after silking, which probably resulted in the additional N not being available for plant growth in 1988. Increased available N resulting from a legume cover crop like hairy vetch may be beneficial in N management programs in lower rainfall areas of the USA when amounts of precipitation are adequate for plant growth and N mineralization.

Winter legumes as a nitrogen source for no-tillage cotton

Winter legumes can serve dual purposes in no-tillage cropping systems. They can provide a no-tillage mulch, and supply a considerable quantity of N for thesummer crops. Cotton ( Gossypium hirsutum L.) was no-tillage planted into crimson clover ( Trifolium incarnatum L.), common vetch ( Vicia sativa L.), and fallowed soil for two years to determine the effects of winter legume mulches on growth, yield, and N fertilizer requirements. The legumes were allowed to mature and reseed prior to planting cotton. The winter legumes produced no measurable changes in soil organic matter, N, or bulk density, but water infiltration was more rapid in the legume plots than in the fallowed soil. In the fallow system, 34 kg ha −1 N fertilizer was required for near maximum yields. In the clover plots, yields without N fertilizer were higher than when N (34 and 68 kg ha −1) was applied. In the vetch plots, cotton yields were highest without N fertilizer the first year, but yields were increased with 34 kg ha −1 N the second year because of a poor vetch seed crop and a subsequently poor legume stand. In the clover plots, a 20–30% cotton seedling mortality occurred in one year, but this stand reduction apparently did not affect cotton yields. Winter legume mulches can provide the N needs for no-tillage cotton without causing an excessive and detrimental quantity of N in sandy soils naturally low in soil N (0.04%). Unless the reseeding legume systems are maintained for at least 3 years, the legumes do not, however, provide an economical N source for cotton when N fertilizer requirementsare low (34 kg ha −1 in this study). A possible disadvantage of the system for reseeding legumes is that cotton planting is delayed 4–6 weeks beyond the normal planting date, which can reduce yields in some years.

The Effect of Longtime Use of Winter Cover Crops on Certain Physical Properties of Commerce Loam

AbstractA study has been made of certain physical properties of Commerce loam as affected by longtime use of winter cover crops preceding cotton. The treatments used were: (1) no treatment, (2) 40 pounds per acre of inorganic nitrogen, (3) common vetch, and (4) hairy vetch. The individual plots were sampled in 1955 and analyses made of the following soil properties: organic matter, total nitrogen, aggregation index, bulk density, noncapillary porosity, water permeability, field capacity, and wilting point.The organic matter and total nitrogen contents were highest in the hairy vetch plots and lowest in the plots receiving 40 pounds per acre of nitrogen and in the untreated plots. The values for aggregation, bulk density, and noncapillary porosity showed that the physical condition of the soil was best in the hairy vetch plots, next best in the common vetch plots, and poorest in the untreated plots and the plots receiving 40 pounds per acre of nitrogen. The 25‐year average per acre yield of cotton from the different treatments was: hairy vetch, 2,000 pounds; common vetch, 1,680 pounds; 40 pounds of nitrogen, 1,470 pounds; and no treatment, 900 pounds. The ability of the 40 pounds of nitrogen to produce an increase in yield over the untreated plots was not reflected in an increased organic matter content or an improved soil physical condition.