Chisel Treatments Research Articles

Species composition of perennial weeds as influenced by mechanical steam treatment

Despite the great aspect of the use of chemical agents for plant protection against weeds, it is not always 100% commensurate with preparations. Since each plant develops immunity to drugs over a period of time, thus many agricultural producers strive to improve and find new methods of destroying parasites harming plants. Modern agricultural production reasonably puts forward the requirements for increasing the profitability and environmental safety of the products obtained. In this regard, there are great opportunities for the effective use of mechanical and physical methods of weed control, instead of problematic options for the use of herbicides. The improvement of tillage systems, in terms of greening agriculture, is primarily associated with their adaptation to a variety of soil and climatic conditions and in-depth differentiation in accordance with the agro-ecological requirements of crops. An optimally selected tillage system maintains a favorable phytosanitary condition of the soil for plants. Based on previous research in this area, the experience was studied and referred. The article presents the results of the number of treatments for the predominant weeds in the Southern Federal District of the Russian Federation. Taking into account early studies, it was revealed that due to the increased share of grain crops in the crop rotation, the amount of weed vegetation in the field increases over the years. We chose the chisel treatment method by the working bodies of the "Ranch" with a reservoir turnover of 0.12-0.15 m. When taking into account the clogging, the methods of A.M. Tulikov were used. There is a noticeable reduction in the contamination of certain plant species in all the years of the study for 2020-2022. Therefore, the goal was set to study each type of weed vegetation after cultivations prevailing in the Southern Federal District. The results were reliable and complete. By carrying out multiple cultivations, it was possible to identify weed vegetation most susceptible to processing by chisel organs of the "RANCH" without the introduction of chemical means of protection.

Influence of agricultural practices and sowing dates under different weather conditions on soybean yield

The article is devoted to determining the optimal sowing time for soybeans with stable warming of the soil, considers the processing with a stratifier PRSM-5 and chisel processing against the background of pre-sowing rolling. Using soil-cultivating units of three types, an analysis was made of the effectiveness of various methods of basic cultivation against the background of various agricultural practices. The optimal timing of soybean sowing was determined with stable heating of the soil to 8–10 o С when treated with a stratifier PRSM-5 and up to 10–12 o С during chisel cultivation against the background of pre-sowing rolling. The obtained results of the research showed that the soil density depends primarily on the method of basic cultivation. The analysis of soil density indicators as a whole showed that after treatment with the stratifier PRSM-5 it was somewhat less and averaged 1.04 g/cm3 , and after chisel treatment – 1.09 g/cm3 . The analysis of the structural composition of the soil showed that the best structural structure of the soil was noted when processing with a stratifier PRSM-5 due to the removal of the most agronomically valuable soil lumps from the lower layers to the surface, here the structural coefficient was high and reached 2.36, and with chisel processing – 2.08. An analysis of the reserves of productive moisture at the end of the growing season showed that during chisel processing they were used more rationally, and significantly decreased in the phase of full ripeness after processing with a stratifier PRSM-5 – they amounted to 57 mm, and after chisel processing – 69 mm. The experimental data obtained indicate that under dry weather conditions, the best yield was formed when treated with a stratifier PRSM-5 at the second sowing date, and when chisel loosening - during the first and pre-sowing rolling. Key words: soybean, tillage, stratifier PRSM-5, density, structure, yield.

Influence of cultivation of secondary mung bean, soybean and oat crops on cotton yield and soil structure by different methods of tillage after winter wheat

This article provides information on the results of scientific research aimed at maintaining and increasing soil fertility in the country and in the world today, as well as ways to increase it, as well as the impact of organic fertilizers on soil fertility. The article presents evidence-based data on the study of the effect of soybean, mung bean and oat sowing in different ways with deep, medium and shallow tillage after harvesting winter wheat in conditions prone to wind erosion with low fertility, on the mechanical composition of light irrigated meadow saz, slightly saline soils for the number of bacteria accumulating nitrogen in the roots of legumes and root crop residues macroaggregates in the soil between the options increased by 0.1-10%, soil porosity by 0.6-1.5, humus content by 0.001-0.004%, total nitrogen by 0.005%, the content of nitrate nitrogen by 0.1-3.6 mg/kg. In the variants with row crops of soybean and mung bean after tillage to a depth of 30 cm after winter wheat, the yield of mung bean grain was 16.5 c/ha, and soybean 18.8 c/ha, where the mung bean yield was higher by 2.1 c/ha, and soybeans by 2.5 c/ha compared with chisel treatment to an average depth of 22-24 cm. tillage to a depth of 14-16 cm using a cultivator. With ordinary sowing, mung bean achieved a profitability of 48.1%, and soybeans 52.7%. When growing cotton next year against the background of row sowing of repeated crops of mung bean and soybeans with a plow to a depth of 30 cm after harvesting winter wheat, the yield from cotton sown after mung bean was 33.4 centners / ha, and after soybeans 34.2 centners / ha and the level of profitability increased by 39.5%.

Изменение фосфорно-калийного режима черноземов обыкновенных в длительном опыте Ростовской области

The change in the content of mobile phosphorus and exchangeable potassium in calcic chernozem of the Rostov region has been studied. The use of chisel treatment on an erosion-hazardous slope reduced soil flushing by 12.6%. By the end of the first rotation of the grain-to-crop crop rotation, when using an extensive fertilizer application system, a decrease in the content of mobile phosphorus and exchangeable potassium was noted. Over the seven rotations of the crop rotation, this difference continued to increase. Systematic application of fertilizers in various doses allowed to increase the content of mobile phosphorus by 145.1-151.6%, exchangeable potassium - 21.1-24.1% compared to the initial content. Tillage had a negligible effect on the content of mobile forms of plant nutrition elements. Keywords: CALCIC CHERNOZEM, MOBILE PHOSPHORUS, EXCHANGEABLE POTASSIUM, CROP ROTATION, LONG-TERM EXPERIENCE

Effects of tillage method and drainage management on some soil physical properties

Tillage is one of the most important practices affecting soil physical and hydraulic properties. Its effects may vary intensely according to the tillage method. This study aims to evaluate the effects of different tillage methods (moldboard plow+disk harrow, moldboard plow+rotary tiller and chisel plow+disk harrow) and drainage (subsurface drainage and non-drainage) on soil physical properties in a clay loam soil. The experiment was conducted in split-plot in time statistical design. Soil bulk density, aeration porosity, organic matter, aggregate mean weight diameter (MWD) and water infiltration rate were measured after planting and after harvesting of winter-wheat crop. Results revealed that the tillage method had significant effect on organic matter content, such that the lowest (1.18%) and highest (1.35%) values were observed in moldboard plow/disk harrow and chisel treatment, respectively. Tillage effect was significant on saturated moisture content, MWD, aeration porosity and infiltration rate. The effect of time was significant on all investigated factors. The effect of drainage was significant on MWD and infiltration rate. Evaluating the interaction effect of tillage and drainage indicated that the contribution of drainage on changing MWD is higher than the tillage methods. Further, it was concluded that the selection of tillage method had an important role on aeration porosity and MWD in no drainage condition, so that moldboard plow makes much more aeration porosity (25.48% against 17.17%) and less MWD (2.40 against 2.80 mm) compared to chisel. According to the result, the treatment combination including drainage/after planting/moldboard plow and disk harrow had the lowest MWD and also, combined treatment of no drainage/after harvesting/chisel plow) had the highest MWD. The application of chisel is not recommended in no-drained areas having high level of groundwater, because of the highest saturated moisture content and MWD along with the lowest aeration porosity compared to moldboard plow.

Long term impact of different tillage systems on carbon pools and stocks, soil bulk density, aggregation and nutrients: A field meta-analysis

Intensive tillage frequently has adverse impact on soil physical quality and soil organic carbon stocks in temperate regions. A consequence of this has been a reduction in crop production over the years demonstrating the necessity of effective and sustainable agriculture. This study aimed to evaluate soil organic carbon (SOC) storage and pools, soil bulk density, aggregation and nutrient availability under different tillage systems (no-tillage, chisel and conventional tillage), based on a long field experiment. After 10 years of crop rotation, in 0–30 cm soil depth, no-tillage system had higher total organic carbon over conventional tillage treatment. Plots under no-till and chisel treatments in 0–10 cm depth, had 7–13%, 34–35% and 9–15% higher non-labile fraction (Cfrac4), very-labile fraction (Cfrac1) and total organic carbon (TOC), respectively compared to that of conventional ones. Also, no-till system had higher passive carbon pool and carbon management index than conventional system. In addition, the conservative tillage, reduced soil bulk density compared with conventional tillage in the surface layer. The stability of slow-wetting and room storage aggregates from conservative tillage were significantly higher (p < 0.05) than conventional tillage. Overall, stability of soil aggregates is improved under conservative tillage. Tillage system, crop rotation and residues, increased soil available nutrients N, P and K in the 0–10 cm depth, with the highest values in no-tillage system. Therefore, conservation tillage could be recommended as a tillage practices that improve fertility soil characteristics and production sustainability.

Вплив різних способів обробітку ґрунту на агрофізичні показники чорнозему типового Правобережного Лісостепу України

В статті подані значення та завдання різних способів та систем обробітку за вирощування сої за різних попередників. Встановлено, що мінімізація обробітку веде до підвищення щільності оброблюваного шару ґрунту і зменшення загальної щілинності (пористості). Найкращі умови для росту і розвитку сої складалися за проведення оранки та чизельного обробітку на 20–22см, де показники щільності і пористості ґрунту, залежно від попередника, варіювали від 1,28 до 1,33 г / см 3 і від 49,0 до 50,9 % відповідно. За мілкого безполицевого і поверхневого обробітків ґрунту щільність формувалася у межах 1,36–1,39 г / см 3 залежно від попередника, а пористість знижувалась до 46,5–47,8 %. Найвища серед досліджуваних обробітків щільність складення (1,38–1,43 г / см 3 ) і найнижча пористість (44,9–46,9 %) ґрунту були на варіанті за прямої сівби. Найвища урожайність сої отримана після зернових колосових (3,5 0–3,70 т / га) за проведення безполицевого обробітку ґрунту на 20–22 см. Після кукурудзи на зерно і соняшнику найвищу урожайність культури 2,83 і 3,12 т / га отримано за проведення оранки на 20–22 см. За своєчасного і якісного проведення технологічних процесів попередник соя забезпечує урожайність рослин сої на рівні 3,33–3,42 т / га.

Modelling soil water dynamics and crop water use in a soybean-wheat rotation under chisel tillage in a sandy clay loam soil

Mechanical chiseling disrupts the sub-surface compaction often found in agricultural soils, and modifies soil physical condition conducive to root growth. However, the effect is transitory and therefore, the impact on soil hydraulic characteristics and consequently on water dynamics must be precisely quantified for effective technology-targeting. In this study, Hydrus-2D was used to describe the soil water change, root water uptake and profile water balance components under different time lags after chiseling. The input parameters were collected from a 2-year field experiment with soybean-wheat crops in rotation on a sandy loam soil in the experimental farm of the ICAR-Indian Agricultural Research Institute, New Delhi. The chisel treatments were residual (RS), repeated (RC) and no chisel (NC). Greater root water uptake in RS and RC compared to the NC could be attributed to marginally higher leaf area index and fIPAR in chiseled plots along with greater depth and spread of roots. Model simulated soil water content was in good agreement with observed data in the first year of rotation. The model was further validated by comparing the simulated and observed values of crop transpiration with R2 = 0.85 and 0.72 (p < 0.001) in soybean and wheat crop, respectively in the following year. Simulated field water valance components indicated 50–70 mm higher seasonal transpiration by the crops. Chisel plots had significantly higher yield and water use in 1st year soybean-wheat rotation, but the effect of chisel became marginal in the 2nd year rotation. Soil water content profile indicates higher plant-available water in chiseled plots. In view of the cost of chiseling and the marginal benefits obtained till 2nd tear of crop rotation, chiseling once in 2–3 years may be recommended for the sandy loam soils under the semi-arid climate condition.

Accumulation of soil moisture in winter wheat cultivation on slopes of ordinary chernozems of the Rostov oblast

The article discusses the effect of different predecessors and methods of basic treatment of soil on the magnitude and nature of the formation of soil moisture reserves in the cultivation of winter wheat on the slopes of ordinary chernozems in the Rostov oblast. Winter wheat in the experiment was cultivated after a steam clean, after winter wheat, after peas, and after corn silage. The study was conducted in four variants of primary tillage in the following crop rotations: chisel, combo, surface, and moldboard tillage. It is established that, in general, over the growing period of winter wheat, 3 of 4 years have a shortage of water supply, especially in the period from the resumption of the spring growing season to complete full ripeness. Analysis of the autumn watersupplies by variants of the main processing of the soil indicates the advantage of the chisel treatment, confirmed statistically by two predecessors—a clean pair and corn silage. The studies for the years 2011–2014 showed the close relationship of the absorption coefficient of precipitation from the reserves of productive moisture in autumn (R 2 = 0.94). It is revealed that the assimilation of precipitation of the cold period largely depends on soil fertility due to different stocks of productive moisture in autumn. The close relationship of grain yield with the value primary of moisture reserves in the autumn sowing of winter wheat in the soil layer of 0–150 cm is shown.

Sistemas de labranza y densidades de la batata: calidad del suelo y de las raíces tuberosas.

El objetivo de este trabajo fue determinar el efecto de sistemas de labranza y densidades de siembra en la calidad de las raíces tuberosas de batata (Ipomoea batata (L) Lamb.). El estudio se realizó en la Universidad Central de Venezuela, en el año 2014. Se determinaron los grados de severidad de la degradación del suelo y su correspondencia con las escalas de preferencia basadas en el peso unitario y dimensiones de la raíz tuberosa. Se usó un arreglo en franjas, donde los sistemas de labranza (SL) fueron asignados a las parcelas, y las densidades de siembra (Ds) a las franjas. Los SL consistieron en labranza vertical con cincel (LC), con arado de disco (LA), convencional con tres pases de rastra de disco (LCo) y mínima con un pase de rastra de disco (LM). Las Ds fueron de 0,25 cm (D1) y 0,15 cm (D2) en la hilera. La calidad física del suelo fue superior en los tratamientos de LA. De estos, la combinación con la distancia de siembra más larga (LA-D1) favoreció la mayor calidad postcosecha del cultivo. Al contrario, en los tratamientos con cincel se promovió la menor aceptación del consumidor. La ligera a moderada severidad de la degradación del suelo no explicó la variación de la calidad postcosecha. Se in ere sobre la menor tasa de movimiento de agua en LC, que promovió un exceso de humedad y la más baja calidad de la raíz tuberosa.

The role of surface microreliefs in influencing splash erosion: A laboratory study

Wu J., Zhao L., Wu F., Li Z. (2016): The role of surface microreliefs in influencing splash erosion: A laboratory study. Soil & Water Res., 11: 83–89. The detachment and transport of soil particles from soil mass are important effects of falling raindrops on soil erosion during rainfall. The objective of this study was to determine whether soil microrelief affects the detachability and transportability of soil particles by raindrop splash. Experimental microreliefs were manually simulated by two tillage practices: shallow hoeing, contour chisel plowing, and a smooth slope served as control treatment. The experiment included three simulated rainfall intensities (1.0, 1.5, and 2.0 mm/min). A splash board was used to collect sediment splashed upslope as well as that splashed downslope. Results show that microrelief has a positive effect on detachment rate (DRt) and has a negative effect on net downslope movement rate (SPnet). With the exception of DRt of which hoe treatment was less than smooth at the rainfall of 1.0 mm/min intensity, DRt of hoe and chisel treatments were twice as high as that of smooth to other treatments. For all treatments, SPnet of hoe and chisel treatments were less than half of smooth. Regression analysis showed that DRt change with increasing rainfall intensity could be described by a power function for all treatments. The change of SPnet could be described by a logarithmic function for hoe and chisel treatments, while the change of SPnet of the smooth treatment could not be described by a logarithmic function. Statistical results suggest that DRt was significantly influenced by rainfall intensity, while SPnet was not. Conversely, SPnet was significantly influenced by soil microrelief, while DRt was not.

Short-term responses of soil and wheat yield to tillage, corn residue management and nitrogen fertilization

Corn residues management is a major problem in the southern part of Iran where irrigated wheat–corn–wheat rotation is a common practice. A two-year (2008–2010) field experiment was conducted as a factorial split plot design with three replications at the Agricultural Research Centre, College of Agriculture, Shiraz University, Shiraz, Iran to determine the influences of different amounts of corn (Zea mays L.) residues (0, 25 and 50%) incorporation and nitrogen (N) rates (75 and 150kgha−1) on some soil properties, yield and yield components of winter wheat (Triticum aestivum L.) under two tillage systems. Tillage treatments were moldboard plow followed by two harrow diskings and chisel plow tillage followed by a single harrow disking. The soil with chisel treatment had about 8 and 15% more soil organic carbon (SOC) and total N than moldboard plow treatment, respectively. Incorporation of increased amounts of corn residues and a higher N rate reduced C:N ratios in the chisel treatment in both years. Soil electrical conductivity (EC) increased with chisel plow and increasing amounts of residues incorporation and N rates. The lowest pH found in plots with no residue incorporation was 8.1 compared to 8.2 in plots with 50% residue incorporation. For treatments receiving 150kgNha−1, soil pH was significantly higher compared to treatments receiving 75kgNha−1. The highest wheat grain yields (about 8.5tha−1) were obtained with chisel treatment, 25–50% corn residue incorporation and application of 150kgNha−1. Incorporation of 25–50% of corn residues (7500–15,000kgha−1) is recommended to increase SOC in a wheat–corn–wheat rotation in this region.

Strength Properties and Organic Carbon of Soils in the North Appalachian Region

Soil strength influenced by management and soil properties controls plant growth, root development, and soil‐moisture relations. The impact of textural and structural parameters on soil strength is moderated by soil organic C (SOC) concentration. Therefore, the objectives of this study were to assess differences in soil strength and SOC concentration in watersheds under long‐term (&gt;15 yr) management practices in the North Appalachian region on a predominantly Typic Hapludults on undulating slopes (&gt;6% slope). Seven watersheds without field replication under moldboard plow (MP), chisel plow, disk with beef cattle manure (DiskM), no‐till with beef cattle manure (NTm), no‐till with no beef cattle manure (NTnm), pasture, and forest were studied. Cone index (CI), shear strength, bulk density (ρb), volumetric moisture content (θv), and SOC concentration were determined at the summit, backslope, and footslope landscape positions at the 0‐ to 10‐, 10‐ to 20‐, and 20‐ to 30‐cm depths. The SOC concentration was slightly higher at the footslope than at the summit position in the cultivated watersheds. The ρb was lower at the footslope than at the summit in NTm (1.22 vs. 1.42 Mg m−3) and chisel (1.34 vs. 1.47 Mg m−3) treatments. Forest had the lowest CI (0.19 MPa), shear strength (6.11 kPa), and ρb (0.93 Mg m−3) and the highest SOC concentration (62.7 g kg−1), whereas MP had the highest CI (0.67 MPa), shear strength (25.5 kPa), ρb (1.44 Mg m−3), and the lowest SOC concentration (13.6 g kg−1) in the 0‐ to 10‐cm depth (P &lt; 0.01). The SOC concentration in NTm was 1.7 times higher than that in NTnm, and both no‐till treatments had lower ρb (&lt;1.21 Mg m−3) than MP (1.44 Mg m−3) at 0‐ to 10‐cm depth (P &lt; 0.01). Manuring decreased both CI and shear strength, but increased SOC concentration. The ρb, θv, and SOC concentration were potential predictors of CI; whereas ρb and SOC concentration were of shear strength (r2 &gt; 0.42; P &lt; 0.01). Results show that landscape positions had small effect, but management, particularly manuring, had large and significant effects on soil strength and SOC concentration.

Vertical movement of weed seed surrogates by tillage implements and natural processes

Vertical position of weed seeds in the soil column is one of the critical factors governing the density of emerged seedlings, but data on movement of subsurface seeds and seed surrogates by tillage are limited. In this experiment ceramic beads were seeded at 0, 4, 8, 12, 16 and 20 cm using specially constructed equipment. Plots were then tilled at right angles to the bead slots with either a moldboard plow, a chisel plow with curved blades, a chisel plow with straight blades, heavy tandem disks, a rotary tiller, or left untilled. Soil was sampled to determine bead positions. The probability matrix describing movement of beads from each soil layer to any other was estimated for each tillage regimen by maximum likelihood. Movement patterns for moldboard plow, the two chisel plow treatments, and disk and rotary tillage differed significantly. The difference between disking and rotary tillage was only marginally significant (0.05 < P < 0.10), as was the difference between the two chisel treatments. The chisel, disk and rotary tillage treatments all buried at least 70% of surface beads to below 2 cm but they showed little vertical displacement of beads below 10 cm. For example, beads below 14 cm in the chisel treatments had a >80% probability of remaining in at their original depth. Tillage by moldboard plow showed the expected soil inversion, but burial of surface beads was greater than return of buried beads to the surface. For example, the probability of a surface bead ending up below 10 cm was over 77% whereas the probability of a bead originally in the 14–18 cm layer moving to the top 10 cm was only 44%. Sampling of the no tillage and moldboard plow treatments the following spring showed an upward movement of beads by natural causes for beads below 14 cm. To allow flexibility in vertically structured population models, the movement probability matrices were fitted with a continuous model based on the beta distribution. The model showed that for a hypothetical uniformly distributed seed bank, 97% of seeds in the top 4 cm following moldboard plowing had arrived there from greater depths. In contrast, only about one third of seeds in the top 4 cm of soil after tillage by chisel, disk or rotary tiller arrived from deeper layers.

EFFECT OF IMPLEMENT ON SOIL CO2 EFFLUX: FALL VS. SPRING TILLAGE

Assessing strategies to help mitigate the rise in atmospheric CO2 includes evaluation of management decisions concerning tillage practices that influence soil carbon loss. Information is lacking on seasonal CO2 efflux patterns, as affected by degree of soil disturbance/residue mixing and time of tillage operations. An experiment was conducted following a grain sorghum [Sorghum bicolor] (L.) Moench.] crop on a Norfolk loamy sand (Typic Kandiudults) in east-central Alabama to characterize soil CO2 efflux patterns as affected by tillage implement (disk-type, chisel-type, and undisturbed) and time of soil disturbance (fall and spring). Soil CO2 efflux assessment began immediately following fall tillage and continued for a period of about six months. Measures were also taken in the spring after imposing tillage treatments on another set of plots. Concurrent measures were also made on undisturbed plots. For fall measurements, increased CO2 efflux was related to degree of soil disturbance. Losses were similar for the chisel and undisturbed treatments and lower than the disk treatment; cumulative efflux estimates also reflected such differences. With spring tillage, CO2 losses for the undisturbed and disk treatment were similar, while the chisel treatment exhibited a slightly lower loss. Results suggest that selection of fall tillage equipment that maintains surface residue and minimizes soil disturbance could help reduce CO2 loss. However, such considerations for spring tillage operations would not result in a substantial reduction in CO2 loss.

Constructing an Arable Layer Through Chisel Tillage and Agropastoral Systems in Tropical Savanna Soils of the Llanos of Colombia

ABSTRACT Integration of crop and livestock systems (agropastoralism) is a key strategy for intensifying agricultural production on infertile acid savanna soils, and for reversing problems of soil degradation in the tropics. The main objective of this study was to evaluate the impact of strategies including vertical tillage (1, 2 or 3 passes of chisel), crop rotations (rice-soybean), and agropastoral systems (rice-grass alone pasture; rice-grass/legume pasture) on the build-up of an arable layer and on grain yields of upland rice and soybean. We assessed the build-up of an arable layer in terms of improved soil physical characteristics (bulk density, penetration resistance), soil nutrient availability, soil phosphorus (P) pools, plant growth, and nutrient acquisition during the fourth year after the establishment of different treatments on native savanna soil. The soil used in this study was an Oxisol in the eastern plains (Llanos orientales) of Colombia. Agropastoral treatments (rice-grass alone pasture; rice-grass/legumes pasture) with vertical tillage decreased soil bulk density in the 0–20 cm soil layer by 12% when compared with the unmanaged native savanna. Consistent with bulk density, penetration resistance was also markedly decreased for 0–20 cm depth. Three passes of chisel (rice-soybean rotation) and pasture treatments (grass alone and grass/legume) improved the availability of Bray (II) P, K, Ca, and Mg in the 0–5 cm layer. The biologically available resin-Pi and NaHCO3-Pi each represented 5% of the total P and were significantly affected by chisel down to 10–20 cm depth. The moderately resistant NaOH-P represented, on average, 33% of total P in the 0–20 cm soil layer, and both NaOH-Pi and NaOH-Po were significantly affected by chisel tillage. Results on grain yields of upland rice showed that three passes of chisel could have a negative effect on grain yield, and that yields which declined over time declined more in agropastoral treatments than in rice-soybean rotation. These results indicate that the use of vertical tillage and agropastoral treatments can contribute to the build-up of an arable layer in low fertility savanna soils of the Llanos of Colombia as indicated by improved soil physical properties and nutrient availability. However, to take advantage of the constructed arable layer to improve crop yields, there is a need for developing better crop management strategies to control weeds.

Effect of Tillage Methods on Termite Damage to Maize in South Africa

Fungus growing termites, Microtermes sp. and Odontotermes sp. are important pests of maize in southern Africa. They damage roots and stems of maize plants and cause lodging of plants after senescence. Termite nests are difficult to locate and destroy and no effective method of control has yet been developed. Different tillage methods that could destroy nests were evaluated in the field over two seasons. Tillage methods included deep chisel plough, shallow chisel plough, deep mouldboard plough, rip and rip-on-row. Significant differences were observed in the effect of different tillage methods on lodging of maize plants. The deep mouldboard plough treatment that disturbed and overturned soil to a depth of 0.30 m resulted in significant reduction in incidence of lodged plants. The deep chisel treatment disturbed the upper 0.25 m soil layer and also resulted in a significant reduction in the incidence of lodging. The shallow chisel and rip-on-row treatments had the highest incidence of lodging. Deep tillage methods are, however, not considered to be a long-term solution for termite damage in maize.

ALTERNATIVE N FERTILIZER MANAGEMENT STRATEGIES EFFECTS ON SUBSURFACE DRAIN EFFLUENT AND N UPTAKE

Demonstrating positive environmental benefits of alternative N fertilizer management strategies, without adversely affecting crop growth or yield, was a major goal for the Midwest Management Systems Evaluation Areas (MSEA) program. Our project objectives within this program were to quantify the effects of split- and single-N fertilization strategies on NO3-N concentration and loss in subsurface drain effluent and N accumulation and yield of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. The study was conducted on glacial till derived soils in northeast Iowa from 1993 through 1995 using no-till and chisel plow tillage treatments. One-third of the 2,611 effluent samples had NO3-N concentrations greater than 10 mg L–1. Split applying fertilizer N based on pre-sidedress soil nitrate test (PSNT) results significantly increased corn yield for both tillage treatments in the extremely wet 1993 without increasing NO3-N loss in drain effluent. Increased grain yield also resulted in significantly more N removal. When fertilizer N was applied based on the PSNT, no-till and chisel treatments had similar NO3-N losses and concentrations. Average flow-weighted NO3-N concentrations in drain effluent were not increased when larger amounts of fertilizer were applied based on PSNT. However, prior crop and tillage practices and differences in drain flow volume caused significant differences in NO3-N losses and concentrations. These results suggest that spatial differences in flow volume are a major factor determining NO3-N loss in drainage effluent. Significant differences suggest that combining no-tillage practices with split N fertilizer management strategies can have positive environmental benefits without reducing corn yield.

Infiltration as a tool for detecting soil changes due to cropping, tillage, and grazing livestock

AbstractSoil physical and biological properties often change when different cropping, tillage, or management systems are imposed. Changes occasionally occur quickly, but usually become evident only after months or years. Infiltration rates are affected by several soil properties and may provide the most sensitive indication of changes in soil properties. To evaluate the use of infiltration measurements for detecting changes in soil properties, we conducted infiltration tests on a cropping systems experiment, a tillage experiment, and two beef cattle grazing experiments. In Pennsylvania, significant changes in infiltration rates did not occur until more than four years after converting from a conventional to a low-input cropping system. Infiltration rates were higher on 14th-year no-till plots compared with moldboard plow and chisel treatments in an Iowa tillage study. Earthworm populations and activity were highest in the no-till treatment. Infiltration rates correlated negatively with increased stocking rates in a long-term beef grazing study in Oklahoma. The number of earthworms did not correlate positively with infiltration in this study, suggesting a complex interaction. A short-term study of overwinter beef corn-stalk grazing in Iowa did not show consistent patterns in infiltration rate or other soil properties with different stocking rates. Infiltration appears to be a good indicator of soil structural changes associated with cropping, tillage, and management systems.

Infiltration into Frozen Soil as Affected by Ripping

Frozen soil contributes to water runoff and soil erosion in the inland Pacific Northwest, especially on fields that are fall seeded. Field experiments were conducted on a Walla Walla silt loam near Pendleton, Oregon, to evaluate the use of chisel tillage to increase water infiltration into frozen soil. Tillage at site 1 was with a single 50-mm wide straight chisel. Tillage at site 2 was with l00-mm wide twisted shovels. Water infiltration measurements were made in the fall, in the winter when the soil was frozen, and in the spring. Water was applied at a constant rate using a rainfall simulator. A finite element model (UNSAT2) was used to verify field measurements of water infiltration for the case when the depth of frozen soil was less than the depth of tillage. The finite element mesh was constructed using a vertical slit to imitate the chisel trough. Tillage spacing to minimize runoff was estimated from historic precipitation records, soil macroporosity features, and unfrozen soil permeability. Undisturbed soil cores, 200 200 250-mm deep, were impregnated with paraffin and sliced into serial sections to provide details on macroporosity. Cumulative water infiltration was greatest on chisel treatments, compared to no tillage when the depth of frozen soil was less than the depth of tillage. Increased infiltration on the chisel treatments was attributed to the presence of macropore channels. Serial sections of soil cores collected after the soil thawed confirmed the presence of macroporosity. Simulated water infiltration agreed with field measurements and showed that water infiltration was limited by the permeability of underlying unfrozen subsoil. Results also suggest that shallow tillage improves water infiltration only when the depth of frozen soil does not exceed the depth of tillage.