Clean Tillage Research Articles

Crop residue management and tillage methods for conserving soil and water in semi-arid regions

Soil degradation reduces soil productivity and is a serious problem on much of the land in semi-arid regions. To avert continued degradation, the soil productivity balance must be shifted from degrading processes to conservation practices. Crop residue management and conservation tillage are on the positive side of the balance. When adequate residues are available and conservation tillage is used, soil erosion is greatly reduced and water conservation is enhanced. Water conservation is important for improving crop yields in semi-arid regions, especially where irrigations is not used. A major constraint to residue management in many countries is low production and widespread use for other purposes. In such cases, clean tillage and appropriate support practices such as contouring, furrow diking, strip cropping and terracing may provide adequate soil and water conservation benefits. Where these are not adequate, alternative management practices should be implemented to ease the demand for residues, thus permitting more of them to be retained on the land for soil and water conservation purposes. Some alternative practices include limited or selective residue removal, substituting high quality forages for residues as animal feed, alley cropping, using wasteland areas more effectively, improving the balance between feed supplies and animal populations, and using alternative fuel sources.

Wheat yield depression associated with conservation tillage caused by root pathogens in the soil not phytotoxins from the straw

Wheat planted directly into soil mulched with straw of a previous wheat crop (mulch or conservation tillage) typically grows and yields poorly relative to that planted into a prepared seedbed with straw residue burned or buried (clean tillage). This injurious effect associated with straw mulches has been greatest in the higher-rainfall wheat-growing areas, or in wet years in normally dry areas. Researchers have focused for the past 30 yr on putative phytotoxins thought to be liberated during microbial colonization or breakdown of the straw on or near the soil surface when wet. The results of experiments reported herein indicate that the causal microorganisms are in the soil and not the straw as would be required if phytotoxic straw decomposition products were important. The injury in these experiments resulted from at least three root diseases, all favored by the lack of crop rotation. The three root diseases were take-all caused by Gueumannomyces graminis var. trici, Rhizoctonia root rot caused mainly by Rhizoctonia solani AG8, and Pythium root rot caused by several Pythium spp. The effect of straw on, or mulched into, the soil surface possibly amounts to no more than helping to keep the top 10–15 cm of soil, the zone occupied by the root pathogens, more ideally moist for their activity. The results suggest that conservation tillage is feasible for wheat in the higher rainfall areas when used in combination with a break from wheat.

Preplant Tillage Effects on Irrigated Corn Grown on a Sandy Soil

Sandy soils are extremely vulnerable to wind erosion when bare. Crop residue on the soil surface is an effective control. Crop responses to tillage systems that leave crop residue on the soil surface may differ from clean tillage of sandy soils. A 4-yr study on a sandy soil compared mold board plowing (MP) with two residue conserving tillage systems, no preplant tillage (NPT) and Paraplow (PP), on field corn (Zea mays L.) production. Corn silage yields were similar (about 34 ton/acre) with all three tillage systems. Averaged over the 4 yr, grain yields were significantly affected by tillage in the order PP > MP > NPT with yields of 5.9, 5.6, and 5.2 ton/acre, respectively. Where herbicides had not been applied, large crabgrass [Digitaria sanguinalis (L.) Scop.] populations in MP were 11.1 plants/sq ft compared with 1.6 with PP and 2.6 with NPT. Grain yields on the moldboard plowed plots were about 0.5 ton/acre higher with than without herbicides. These results indicate that tillage systems that leave plant residue on the surface may be used on sandy soils without serious loss of production, especially if the subsoil is loosened.

Environmental Effects on Nitrogen Dynamics in Soybean under Conservation and Clean Tillage Systems

AbstractSoybean [Glycine max (L.) Merr.) obtains required N from the soil via root uptake of mineralized organic matter and fertilizer, and from the air by symbiotic gaseous N2 fixation and ammonia (NH3) absorption. The purpose of this study was to evaluate environmental and tillage effects on dynamic N transport under conservation (NT) and clean tillage (CT) management systems. Soil, plant, and microclimate measurements were made concurrently with estimates of gaseous N2 (using 15N2 techniques) and NH3 uptake from the atmosphere. Soybean growth and N uptake characteristics were similar in both tillage systems, except during a 14‐d drought period, which caused water stress in the CT system, but not the NT system. Nitrogen fixation decreased in the CT system to less than half that of the NT system fixation rate, resulting in a seasonal reduction of 29% in the CT system. Net NH3 transport varied from net absorption by the canopy during periods of adequate soil water to net evolution by the CT system during the drought‐stress period. Integration of the net NH3 flux density curves indicated that approximately 3% of the NT system and less than 1% of the CT system plant N was derived from the atmosphere. Also during the drought‐stress period, there was a net loss of plant N to the soil in the CT system indicated by soil and plant mass balance. Insect infestation was much greater in the NT system, reflecting insects' preference for a higher N crop, resulting in a significant N removal from the system. This study showed that soybean in these systems decreased soil N by about the amount of harvested N yield.

Conservation tillage for soybean in the U.S. Southeastern Coastal Plain

Double cropping of soybean has progressed less rapidly in the U.S. Southeastern Coastal Plains than expected by the ample rainfall and long frost-free season. Post-emergence herbicides, the management of plant residues to reduce water use by cover crops, and a no-till planter with a combination subsoiler are the innovations that have facilitated this new production. Full-season soybean ( Glycine max L.) was planted following a grazed cover crop of winter rye ( Secale cereale L.) or late-season soybean was planted following winter wheat harvest. In both cases, a special planter was used with an integral subsoil shank ahead of the opener. Full-season soybean under conservation tillage produced yields equal to or better than yields in conventional clean tillage. In a dry summer, soybean yields under conservation tillage exceeded conventional tillage because of suppressed early biomass production which conserved stored soil water and favored growth during the reproduction phase of the crop-cycle. Late-season soybean yields behind wheat favored the conservation tillage practice of in-row subsoil-planting into stubble. However, planting in burned-off wheat stubble produced the highest yields in this study. In a dry spring, the cover crop accelerated soil water use which resulted in lower soybean yields under conservation tillage. Comparisons of 76 vs. 97 cm row spacing were inconclusive, but the trend suggests that wider rows conserve water under periods of drought and that the narrower-row configuration favors adequate water regimes.

The effects of in-row subsoil tillage and soil water on corn yields in the southeastern coastal plain of the United States

Soil erosion is a problem in the Southeastern Coastal Plain of the U.S.A. where clean tillage row cropping exists without adequate soil conserving practices. Conservation tillage practices in the region have frequently incorporated in-row subsoiling to overcome root restricting soil layers 0.20 to 0.35 m below the surface. A number of studies have been conducted to determine the benefits of in-row subsoiling and results have been contradictory. The objective of this study was to evaluate the relationships between in-row subsoil and non-subsoil tillage treatments, soil water, and corn grain yields. The study was conducted for two years on an Orangeburg sandy loam (Typic Paleudult). The study contained irrigated and non-irrigated treatments. The four tillage treatments used were (T 1) in-row subsoiler followed by a double disk bedder, (T 2) double disk bedder, (T 3) fluted coulter followed by in-row subsoiler and slot filler tines, and (T 4) fluted coulter. Tillage and planting were accomplished simultaneously. Each corn ( Zea Mays L. ‘Dekalb XL72B’) crop was preceded by fall-planted wheat and the wheat ( Triticum aestivium L. “Coker 747”) was killed with herbicides in the spring before corn planting. Wheat mulch was disked in prior to the bedding treatments and left undisturbed for the two fluted coulter treatments. Corn was planted 0.04 m deep with double disk openers. Soil water potential was maintained above 0.05 MPa in the irrigated corn plots. Forty kg/ha of N was applied at planting and followed 42 days later with eight weekly applications of 50 kg/ha N. In-row subsoiling and irrigation treatments significantly increased grain yields. Irrigated corn grain yields were 12333 and 7872 kg/ha in 1978 and 1979, respectively. Non-irrigated corn yields were 7697 and 4892 kg/ha in 1978 and 1979, respectively. In-row subsoiled to a depth of 0.36 m and non-subsoiled grain yields were 8577 and 7820 kg/ha, respectively. There was no significant difference between bedding and fluted coulter treatments.

Potential Peanut Performance in Double-Cropping Systems1

Abstract The potential for utilizing selected peanut cultivars in multiple-cropping sequences was studied on a Bonifay sand and Tifton loamy sand soil in cropping sequences with grain sorghum, tomato transplants, and cucumbers. The peanut cultivars Pronto, Comet, and Florunner always produced more pods under a 114-day growing period than for a 99-day growing period. In a 99-day growing period, Pronto and Comet produced significantly more peanuts than Florunner. Total sound mature kernels (TSMK) percentages were always greater for a 114—day growing period. Seeding rate did not affect TSMK or OK characteristics. On restricted growth periods (99 days), early-maturing peanut cultivars resulted in higher percentages of TSMK than the late-maturing cultivars. Under small production scale research units, Pronto peanut was planted early – April, or late June – under both clean and conservation type tillage. The moldboard land preparation portion of a tillage experiment resulted in greater yields when peanut was planted early or late in 4-row seeding, but not statistically more than 2-row seeding. Grain sorghum grown at a population of approximately 200,000 plants/ha produced greater yields when planted in July than in August planting. Greater grain yields of sorghum were produced using moldboard land preparation.

Limited Tillage and Energy Use with Furrow-Irrigated Grain Sorghum

ABSTRACT LIMITED tillage was successful for managing continuous grain sorghum with furrow irrigation in the Southern High Plains. Grain yields were generally proportional to seasonal water use. The limited tillage treatment, mulch-subsoiling, increased irrigation water intake by 10 percent and grain yield by 8 percent as com-pared with clean tillage and chiselkig. Another limited tillage treatment, bed-splitting, resulted in yields equal to those for the clean tilled treatment yet cost $14.50/ha less because of lower fuel and labor requirements. Time and fuel energy requirements for limited tillage were only about half those for clean tillage. Mulch-subsoiling net-ted $40/ha more than clean tillage because of the greater yield and lower production cost.

Limited Tillage of Furrow Irrigated Winter Wheat

ABSTRACT CONTINUOUS cropped winter wheat was successfully man-aged with furrow irrigation by use of limited tillage and chemical weed-volunteer control on the Southern High Plains. No-till had slightly higher yields and irrigation water use efficiency than did clean tillage. The yield increase with no-till was generally offset by additional cost of herbicides. Limited tillage seemed more practical and dependable as an alternative to clean tillage. No-till and limited tillage reduced time and fuel requirements by 50 and 40 percent, respectively.

Development of No-Tillage Cropping Systems in Virginia

ABSTRACT j O-TILLAGE crop production IN which incorporates the ad-vantages of vegetative-mulch covers reduces water runoff and soil erosion, minimizes pollution of public water-ways, and reduces energy require-ments. No-tillage corn in a killed vegetative-mulch cover crop out-yielded corn in conventional clean tillage by more than 16 percent during a 14-yr period. Researchers, for many years, have recognized the advantages of vege-tative-mulch covers in reducing water runoff and soil erosion resulting from row crop production, especially on sloping terrain. In 1948, Virginia agricultural engineers attempted to grow corn using a live orchardgrass-clover cover. This resulted in excellent control of runoff and erosion but at the expense of greatly reduced yields. The reduced yields were mainly due to competition for both moisture and plant food from the live mulch. As selective herbicides for control of vegetative-mulch covers and undesirable plants become avail-able in the late 1950's these trials were continued using killed vegetative-mulch covers. All of these and subsequent experiments were sta-tistically designed and replicated four or more times. In 1960, satisfactory corn yields were obtained with no-tillage pro-duction practices in killed vegetative-mulch cover crops ranging from sparse to extremely dense (Lillard et al. 1965). These early studies indi-cated the need for better herbicides and procedures for applying them, and for better planting equipment. They also emphasized the need for additional information on cover crops, soil-moisture relationships, and plant food requirements for optimum results. However early research proved conclusively that corn could be grown without prior seedbed tillage and that yields, under Virginia conditions, compared favorably with those obtainable with conventional clean tillage, Table 1.

No-Till Seeding of Irrigated Sorghum Double Cropped after Wheat

ABSTRACT IRRIGATED grain sorghum was successfully no-till seeded into wheat residue immediately following wheat harvest in the Southern High Plains. Grain sorghum grown with clean tillage and seeding was grown for comparison. No-till seedlings generally emerged faster, grew taller, and matured up to 5 days earlier than controls. Grain yields for a 5-yr study averaged 5,690 kg/ha for no-till and 5,070 kg/ha for clean-till, a 12 percent increase. No-till required only one-fifth as much time between crops to prepare and plant a seedbed. No-till reduced fuel requirements, including harvest, by 55 percent.

Effect of Fertility Treatments on the Growth, Chemical Composition and Yield of No‐Tillage Corn on Orchardgrass Sod1

AbstractMany data are available on the relative efficiencies of various fertility treatments for corn (Zea mays L.) when grown by the conventional methods of clean tillage. Few data are available, however, on the relative efficiencies of sources and rates of N, P, and K on the growth, chemical composition, and yield of corn grown with the notillage system.An experiment was conducted at Blacksburg, Virginia, on Groseclose silt loam (Typic, Hapludults; clayey, mixed, mesic) to determine the effects of 168 and 280 kg N/ha, 0 and 100 kg P/ha from partially and fully acidulated rock phosphate, 25 kg P/ha from fully acidulated rock phosphate, and 140 kg K/ha from KCI and K2~SO4 on the growth, chemical composition of leaves and yield of notillage corn on a chemically killed orchardgrass sod.Growth was significantly slower with the higher rate of N, but significantly increased with increased rates of applied P. Plant growth rate was unaffected by sources of K. Leaf concentrations of N and K were unaffected by rates of N and sources of K, respectively, but the P and K concentrations were significantly increased with the higher P rates. Leaf Mn concentration was higher with the higher rate of N than with the lower rate. The Ca, Mg and Mo concentrations in the leaf increased with P fertilization, but the Zn concentration decreased with P fertilization.Corn yields were significantly higher with concentrated superphosphate than with partially acidulated rock phosphate applied at the same rate of P. The higher rate of N resulted in a significant reduction in grain yield of 552 kg/ha. There was no response to S in the K2SO4.

Effect of Rotations, Tillage Methods, and N Fertilization on Winter Wheat Production1

AbstractWinter wheat (Triticum aestivum L.) was grown continuously and in rotation with alfalfa (Medicago sativa L.) or grass on Pond Creek and Grant silt loams in the 64‐cm rainfall area of north central Oklahoma. Studies were conducted from 1956 through 1967. Stubble mulch and clean tillage were compared in continuous wheat and alfalfa‐wheat systems. The principal effect of alfalfa on wheat yield was to supply N. Wheat in rotation with alfalfa (3 years alfalfa, 3 years wheat) yielded 2,020 kg/ha, while continuous wheat fertilized annually with 45 kg N/ha yielded 2,180 kg/ha. Yields of wheat in a grass‐wheat rotation were inferior to those of continuous wheat plus N because of N deficiency.Without N fertilizer, clean‐tilled continuous wheat outyielded stubble‐mulched continuous wheat by 23% (clean tilled: 1,790 kg/ha; stubble‐mulched: 1,460 kg/ha). With 45 kg N/ha, the advantage for clean tillage was reduced to about 8% (clean tilled: 2,160 kg/ha; stubble‐mulched: 2,000 kg/ha). The 45 kg/ha N fertilizer rate was sufficient for near maximum wheat yields under both clean and stubble‐mulch tillage.

Bulk Density, Aggregate Stability, and Organic Matter Content as Influenced by Two Wheatland Soil Management Practices

AbstractThe amount of organic matter in the top 15.0–30.5 cm of a Grant silt loam after 11 years of stubble mulching was significantly greater than that in clean tilled (plow) plots on this soil over the same time period. Aggregation under stubble mulching was greater than with clean tillage. Soil compaction was noted by an increase in bulk density at the 23.0–30.5 cm depth in clean tilled plots, but was absent at all depths measured in stubble mulched plots.Annual nitrogen applications gave a significant increase in organic matter content at the 15.0–23.0 cm soil depth. Stubble mulching in an alfalfa (Medicago sativa L.)‐wheat (Triticum aestivum L.) rotation program was shown to influence the soil physical properties more significantly than did stubble mulching in a continuous‐wheat or the clean tillage in an alfalfa‐wheat program.

Mulch Tillage: Some Effects on Plant and Soil Properties

AbstractThe effects of a “double‐cut plow” method of mulch tillage on fertility, as measured by soil nitrate‐N, soluble nutrients in leaf, grain yields, and nutrient content of the corn plant, and on physical properties of the soil were investigated at Blacksburg, Va. The standard 3‐year rotation of corn, small grain, and clover‐grass with mulch tillage practice during the corn year was compared with a similar rotation using conventional clean tillage practice.The percentage of N in the corn plant was lower where mulch tillage was used. The differences were significant (5% level) for high yield seasons. Percentage P in the plant was not affected by tillage method. Differences in K content of corn plant between tillage method, although usually large, were inconsistent. In general, soil nitrate‐N and soluble N‐P‐K in leaf tissue were lower during the early part of the growing season under mulch tillage.Significant reduction in yields (19 bu./A.) were obtained from mulch in 1948. This was apparently due to a similar reduction in stand. In 1949 and 1950, with planter modifications which pushed the mulch from the row, comparable yields and stands were obtained. Three‐year average yields were: mulch 73 bu./A., turn plow 81 bu./A.The 0–3 inch layer of soil under mulch showed higher aggregation, air space, percent organic matter, and percent total nitrogen than did conventional tillage.There are a number of factors which may affect the availability of nutrients where this tillage method is used. It is believed that the lower N status under mulch was due chiefly to changes in the soil microflora brought about by this tillage.