Ridge Tillage System Research Articles

Effect of Soil Tillage Systems and Crop Seasonality on the Sediment Geochemical Properties Transferred into a Headwater: A Case of Study in Tobacco Plantation

ABSTRACT The global impacts of agricultural land conversion on soil erosion and pollution, particularly in tobacco cultivation areas, are well-recognized as significant contributors to soil degradation. These areas are identified as hotspots for environmental concerns due to practices that lead to increased erosion and pollution. From this perspective, this case of study explores fine sediment samples from two areas with tobacco cultivation under different tillage systems and seasonal variations, transport into a headwater, and evaluates, on a local scale: (1) the impact of tillage systems on the geochemical signature of sediments; (2) if whether crop seasonality affects these sediment geochemical signatures. The Conventional Ridge Tillage (CRT) system involves extensive soil exposure and machinery for soil management, while the Mulch Ridge Tillage (MRT) system prioritizes soil conservation and relies on herbicides for weed control. The analytical methodology used to assess the sample element characteristics was Energy Dispersive X-ray Fluorescence (EDXRF). It was applied on the twenty fine sediments (ten of harvest and ten of inter-harvest season of tobacco) to quantitatively assess their inorganic composition. Additionally, Pearson correlation analysis, Hierarchical Cluster Analysis (HCA), and Principal Component Analysis (PCA) were applied on the EDXRF data to highlight the similarities and, thus, providing information to assess the complex data clustering patterns. As a result, the sediment compositions from the two studied soil systems are not similar. The PCA showed that the CRT sediments are characterized by the P, S, K, Ca, and Mn content, presenting a geochemical signature related to manure and fertilizer compared to the MRT, which is correlated with Al, Ti, Fe, Cu, and Zn contents, exhibiting a geochemical signature characterized by the natural soil composition. Therefore, the sediment geochemical signatures might be affected by two phases in the study area: a) tillage system characteristics and b) seasonal soil erosion. These findings underscore the importance of managing soil nutrients to mitigate soil pollution and nutrient exportation to aquatic systems. Moreover, the results emphasize the recommendations for sustainable agricultural practices in tobacco-growing areas to protect environmental quality.

Impacts of straw mulching in longitudinal furrows on hillslope soil erosion and deposition in the Chinese Mollisol region

In the Northeast Mollisol region of China, straw mulching has a great effect on preventing soil loss from ridge tillage, but how furrow straw mulching (FSM) impacts the spatial distribution of erosion-deposition and sediment sources in longitudinal ridge tillage systems is still unclear. Therefore, this study was to quantify the effects of the FSM on the spatial distribution of soil erosion-deposition and sediment sources in longitudinal ridge tillage systems by using the magnetism tracing methodology and indoor simulation rainfall experiments. The experimental treatments included two surface treatments: without the FSM (NFSM) and with the FSM of 0.30 kg·m−2 amount, two rainfall intensities of 50 and 100 mm h−1 were included; each experiment was run for 60 min at a soil pan with a 5° slope gradient, 6.2 m length, 1.3 m width and 0.7 m depth. The results indicated that, compared with the NFSM treatment, the total slope runoff and soil loss in the FSM treatment at two rainfall intensities were decreased by 41.6 % and 99.5 % and by 37.9 % and 97.7 %, respectively, and the reduction in slope runoff and soil loss decreased with an increase of rainfall intensity. The total mass of sediments intercepted by straw mulching on the entire slope accounted for 36.9 % and 10.4 % of the total soil loss in the NFSM treatment, respectively. Erosion regimes dominated on the hillslope of the NFSM treatment with strong-weak alternation at two rainfall intensities, while for the FSM treatment, only deposition regime was observed at 50 mm h−1 rainfall intensity; a slight change with erosion-deposition on the ridge tops was observed and deposition in the furrows was observed at 100 mm h−1 rainfall intensity. Furthermore, the FSM treatment changed the main sediment source from ridge tops to furrows on the hillslope compared to the NFSM treatment, whose sediment contributions from the ridge tops and the furrows at the two rainfall intensities were approximately 16.4 % and 83.6 %, respectively. In conclusion, FSM should be promoted due to its high efficiency in decreasing slope runoff and intercepting sediments. The findings of this study served as a scientific reference for effectively controlling soil erosion along slopes in the Chinese Mollisol region.

Prospects of sediment deposition at small watershed scale in the black soil region of Northeast China: A mini review

Sediment deposition is one of the most significant processes in small watersheds characterized by gentle long hillslopes in the black soil (Mollisol) region of Northeast China, as indicated by severe ephemeral gully and gully erosion on hillslopes and very low sediment concentrations in river systems. Few reviews have been conducted to summarize the related research in this region. The objectives of this review were to identify the potential factors influencing sediment deposition, review related studies, and propose future research needs in the black soil region of Northeast China. Sediment deposition is controlled by the deficit between sediment transport capacity of flow and sediment load. Hence, all factors affecting flow transport capacity and sediment load directly affect sediment deposition. For a specific small watershed, the change in slope gradient along the flow path is the key factor affecting sediment deposition. Shelterbelts, ridge tillage systems, terraces, grass strips, road distribution, ponds and reservoirs, and land-use patterns also influence the spatial distribution and rate of deposition. The trace method has been widely used to quantify sediment deposition in this region. The results of cesium-137 (137Cs), lead-210 (210Pb), and magnetic susceptibility reveal that serious deposition occurs on the back and foot slopes. Distinct deposition occurs in front of contour shelterbelts. Future studies should focus on the methodology, spatial and temporal variations, dominant influencing factors and their mechanisms, and the potential effects on land productivity within specific small watersheds and across the black soil region. This review provides insights into the sediment deposition process in small watersheds characterized by gentle, long hillslopes.

Weed Management in Ridge Tillage Systems—A Review

Although different modifications of ridge tillage (RT) systems exist in different regions around the world, the positive impacts of RT on crop yields and weed management are quite similar. This review gives a comprehensive summary of different forms of RT and highlights the benefits of RT for crop growth, mainly due to better access to soil moisture, nutrients and light. In temperate areas, RT can accelerate crop emergence because soil temperature is usually higher on the ridge. These stimulating effects increase crop competitiveness against weeds especially in the early period of crop development until canopy closure. RT with crops placed on the top of ridges can also be used for automatically guiding inter-row hoes and intra-row band sprayers. The ridges can replace automatic vision control systems for hoeing and band spraying, which are needed for precise weeding in conventional flat seedbeds. Therefore, RT can be considered a possible platform for smart/robotic weeding. This paper introduces a new RT system using real-time kinematic (RTK) global satellite navigation systems (GNSS) for the ridging and seeding of maize and soybean on top of recompacted ridges. Straight ridges with precise positioning data were used to guide mechanical weeding elements precisely along the crop rows. Simultaneously, weeds in the valleys were suppressed by living mulches. Field experiments with this new technology in maize showed 85.5% weed dry biomass suppression compared to an untreated control and a slightly higher weed control efficacy than mechanical weeding in flat seedbeds.

Discrimination of soil losses between ridge and furrow in longitudinal ridge-tillage under simulated upslope inflow and rainfall

Longitudinal ridge-tillage greatly enhances hillslope soil erosion due to increased flow concentration in furrows and sediment delivery from ridge sideslopes. Currently, contributions of upslope inflow and rainfall to soil loss and identification of sediment sources in a ridge-furrow system are still unclear. A set of experiments on 10-m long, 2-m wide field runoff plots at a 5° slope gradient were conducted in the Chinese Mollisol region to quantify the effects of upslope inflow and rainfall on hillslope erosion and to discriminate sediment contributions between ridges and furrows in a longitudinal ridge-tillage system. The experimental treatments included five upslope inflow rates alone (10, 20, 30, 40 and 50 L min−1), two rainfall intensities alone (50 and 100 mm h−1) and the five inflow rates combined with the two rainfall intensities. A stereoscopic photogrammetry method was used to measure micro-topographic conditions before and after each run. The results showed that, compared with the inflow-only treatments, soil losses increased by 1.4–5.2 times and 2.5–14.0 times under the combined treatments of the five inflow rates and two rainfall intensities, respectively. The contributions of the synergistic effects increased with the increase of rainfall intensity. Moreover, in the five upslope inflow-only treatments, soil erosion mainly occurred in the bottom of furrows and ridge toe slopes; while for the combined treatments, ridge sideslope erosion dominated as soil loss from ridge areas accounted for 51.3 %–60.9 % and 53.0 %–61.8 % for the 50 and 100 mm h−1 rainfall intensities, respectively. Therefore, ridge sideslope erosion may be the main sediment source in the longitudinal ridge-tillage system under the bare conditions.

The changing dynamics of rill erosion on sloping farmland during the different growth stages of a maize crop

AbstractRill erosion is a serious concern in the hilly region of China with purple soil, and maize is extensively cultivated in this region. Evaluations of the dynamic mechanisms of rill erosion in sloping farmland areas are particularly important during the maize growing season to determine whether rill erosion can occur. A new ridge tillage (RT) system was designed using local agricultural methods in China. Twelve artificial rainfall experiments were conducted in three 1 × 2 m experimental plots with a slope of 15°, which is a typical slope in the study area. The rainfall intensities were designated as 1.0, 1.5, and 2.0 mm min−1. The rainfall experiments were performed in the field to determine the characteristics of run‐off and sediment transport related to rill erosion processes during different stages of maize growth and to analyse how hydraulic parameters and the sediment yield of the rill erosion process are related. The results showed that rill flow patterns were mainly classified as subcritical transition flow during all the growth stages of maize. The effects of hydrodynamic parameters on the sediment yield were ordered as follows: Reynolds number > stream power > Froude number > shear stress. The total sediment yield varied by stage as follows: seedling stage > jointing stage > mature stage > tasseling stage. The sediment yield and run‐off rate exhibited a linear relationship that was well described at the hillslope scale. To initiate soil loss in sloping farmland areas with purple soil during the maize growing season, the critical hydrodynamic shear stress and stream power must be at least 46.505 Pa and 1.541 N m−1 s−1, respectively.

Weed Seedbank and Weed Biomass Dynamics in a Long-Term Organic Vegetable Cropping Systems Experiment

AbstractMost previous research on changes in weed abundance and community composition in cropping systems has focused on field crops. The study presented here examined changes in the weed seedbank and aboveground biomass in four organic vegetable cropping systems over a 10-yr period. The systems included an Intensive system with six crops per 4-yr rotation, an Intermediate system with one cash crop per year, a Bio-extensive system with alternating cash crop and tilled fallow years plus prevention of seed rain, and a Ridge-tillage system with one cash crop per year. Systems also differed in the types and number of cover crops between cash crops. During the course of the experiment, the weed community shifted from one dominated by summer annual broadleaf species that reproduce at the end of their lives to a community dominated by summer and winter annuals that mature rapidly. This shift in community composition can be attributed to the change in land use from conventionally managed corn (Zea maysL.) and alfalfa (Medicago sativaL.) to organic vegetable production. In particular, crop rotations with diverse preplantings and postharvest tillage dates interrupted the life cycle of common lambsquarters (Chenopodium albumL.) and pigweed species (Amaranthusspp.: mostly Powell amaranth [Amaranthus powelliiS. Watson], with small numbers of redroot pigweed [Amaranthus retroflexusL.] and smooth pigweed [Amaranthus hybridusL.]), while favoring a diverse assemblage of quickly maturing species. The study thus demonstrates that an appropriate crop rotation can control the seedbank of weeds likeC. albumthat potentially persist well in the soil. The Ridge-tillage system greatly reduced the frequency and depth of tillage relative to other systems while effectively suppressing perennial weeds. The early-reproducing annuals, however, became more abundant in the Ridge-tillage system than in the other systems, primarily due to escapes along the edge of the scraped ridges. The tilled fallow periods coupled with prevention of seed rain in the Bio-extensive system substantially reduced weed abundance through time and relative to the other systems.

Weed Abundance and Community Composition following a Long-Term Organic Vegetable Cropping Systems Experiment

Weed management is a major constraint in organic cropping systems. In 2004, the Cornell Organic Vegetable Cropping Systems Experiment was established in central New York state using a split-plot randomized complete block design with two crop rotation entry points (split-plot factor). Four organic vegetable cropping systems that varied in cropping intensity and tillage (main plot factor) were compared: (1) intensive, (2) intermediate, (3) bio-extensive, and (4) ridge tillage. The basic crop rotation was cabbage, lettuce, potato, and winter squash, with additional short-season crops in the intensive system and with cover crops and fallow substituted for cabbage and potato in the bio-extensive system. In 2014, two uniformity trials were conducted in which oat and then a mixture of sorghum-sudangrass plus Japanese millet were grown uniformly over the entire experiment. Prior to sowing oat, soil samples were collected from each plot and an emergence bioassay was conducted to assess the soil weed seedbank. Crop biomass, weed density, and weed biomass were sampled in the uniformity crops. Soil weed seedbank density was three to four times greater in the intensive, intermediate, and ridge-tillage systems than in the bio-extensive system. The bio-extensive system also had lower weed density and weed biomass in the oat uniformity trial compared with the other three systems. Oat biomass did not differ between the cropping systems. Weed density and biomass in oat were also affected by the crop rotation entry point. Cropping system legacy effects on weed abundance and community composition were greater in the oat than in the sorghum-sudangrass plus Japanese millet uniformity trial. Our results illustrate the effects of different organic vegetable production practices on weed community structure and highlight the value of tilled fallow periods, cover crops, and prevention of weed seed rain for reducing weed populations.

Effect of Tillage on the Growth and Yield of Cowpea Varieties in Sudan Savanna Agroecology of Northern Nigeria

Field study was conducted during the rainy seasons (July-November) of 2007, 2008, 2009 and 2010 at the Research Farm of the International Institute of Tropical Agriculture (IITA) Minjibir, Kano State, Nigeria; to compare responses of six cowpea varieties to tillage. The treatments consisted of tillage systems (zero tillage, flat tillage and ridge tillage) as the main plot and cowpea varieties (IT89KD-391, IT90K-277-2, IT97K-461-4, IT97K-499-35, IT98K-131-2, and IT98K-506-1) as the sub-plot. The treatments were arranged as split plot laid out in a randomized complete block design with four replications. Zero tillage was significantly superior in influencing days to maturity, canopy height, intercepted Original Research Article Ewansiha et al.; ARRB, 5(3): 275-284, 2015; Article no.ARRB.2015.030 276 photosynthetic active radiation (IPAR) and leaf area index but not total dry matter and grain yield of cowpea. A positive and significant association was recorded for days to physiological maturity and canopy height across the tillage systems with a correlation coefficient of ≤ 40% for days to maturity and ≥50% for canopy height. Though flat tillage showed a positive correlation with intercepted photosynthetic active radiation (IPAR) and leaf area (LAI), but this association was not significant. However, ridge tillage showed a positive and significant correlation with IPAR and LAI (r =0.378*** and 0.384***). All the tillage systems showed a high and significant positive correlation with cowpea dry matter and fodder yield (r= 0.54*** to 0.77***). Across varieties, grain yield was better with flat tillage than zero and ridge tillage systems, with 10% yield advantage over the two. Zero and ridge tillage were similar in their effects on grain yield. Except for IPAR, LAI and total dry matter (TDM), the interaction effect of cowpea varieties and tillage systems was significant. Our result point to the fact that extensive soil tillage (especially, conventional tillage) may not be necessary for cowpea production in this agro-ecology with a high percentage of sand and a sandy loam as soil textural class. Following our result, we may recommended varieties for the different tillage systems as follows: IT98K-131-2, IT97K-461-4, IT90K-277-2, IT98K-506-1 (grain) and IT89KD-391/IT97K-4614 (best for fodder) for zero tillage system; IT90K-277-2, IT97K-499-35, IT98K-131-2 and IT98K506-1(grain) and IT89KD-391/IT97K-499-35 (best for fodder) for flat-tillage; IT98K-131-2, IT90K277-2, IT98K-506-1 and IT97K-464-4(grain) and IT90K-277-2/ IT89KD-391 (best for fodder) for ridge tillage).

Ridge Tillage Concentrates Potentially Mineralizable Soil Nitrogen, Facilitating Maize Nitrogen Uptake

Ridge tillage (RT) can promote increases in soil C and aggregation at greater rates than conventional tillage, but few studies have investigated how RT may affect soil N distributions across the row/inter-row space. Using a spatially intensive sampling design, we monitored soil potentially mineralizable N (PMN), inorganic N, and plant tissue N in a field study comparing RT and chisel plow (CP) systems. Experiments were fully replicated at two sites in Urbana, IL and Mason, MI during the 2012 growing season. At both sites, a strong interaction effect of tillage × row position was observed for PMN (Illinois, p = 0.005; Michigan, p = 0.02) with higher levels of PMN in the in-row (IR) position than off-row (OR) and between-row (BR) positions of RT treatments following re-ridging. Plant tissue analyses indicated a significant RT advantage at both sites (Illinois, p = 0.04; Michigan, p = 0.02), and a structural equation modeling (SEM) analysis indicated that PMN at the 0- to 5-cm depth in the IR position following re-ridging had a significant effect on inorganic N at the same position and, in turn, a strong influence on plant tissue N (comparative fit index = 0.86, standardized root mean square residual = 0.11, Akaike wt. = 1). Overall, our results suggest that RT can establish soil functional zones (SFZ) with distinct N profiles and that the relocation of PMN in-row may increase the spatial efficiency of N provisioning relative to conventional tillage.

Spatial distributions of soil chemical and physical properties prior to planting soybean in soil under ridge‐, no‐ and conventional‐tillage in a maize–soybean rotation

AbstractDetailed information on the profile distributions of agronomically important soil properties in the planting season can be used as criteria to select the best soil tillage practices. Soil cores (0–60 cm) were collected in May, 2012 (before soybean planting), from soil transects on a 30‐yr tillage experiment, including no‐tillage (NT), ridge tillage (RT) and mouldboard plough (MP) on a Brookston clay loam soil (mesic Typic Argiaquoll). Soil cores were taken every 19 cm across three corn rows and these were used to investigate the lateral and vertical profile characteristics of soil organic carbon (SOC), pH, electrical conductivity (EC), soil volumetric water content (SWC), bulk density (BD), and penetration resistance (PR). Compared to NT and MP, the RT system resulted in greater spatial heterogeneity of soil properties across the transect. Average SOC concentrations in the top 10 cm layer were significantly greater in RT than in NT and MP (P = 0.05). NT soil contained between 0.8 and 2.5% (vol/vol) more water in the top 0–30 cm than RT and MP, respectively. MP soil had lower PR and BD in the plough layer compared to NT and RT soils, with both soil properties increasing sharply with depth in MP. The RT had lower PR relative to NT in the upper 35 cm of soil on the crop rows. Overall, RT was a superior conservation tillage option than NT in this clay loam soil; however, MP had the most favourable soil conditions in upper soil layers for early crop development across all treatments.

Effects of conservation tillage on soil aggregation and aggregate binding agents in black soil of Northeast China

Tillage strongly affects the process of soil aggregate stabilization, which involves a variety of binding mechanisms interacting at a range of spatial scales. To understand how binding mechanisms interact to promote soil aggregation, the impacts of three tillage systems (no tillage (NT), ridge tillage (RT) and conventional tillage (CT)) on soil aggregate binding agents (i.e., organic carbon (SOC), microbial biomass and glomalin-related soil proteins (GRSPs)) and aggregation were studied in the black soil of Northeast China. Compared with CT, RT increased all the aggregate-associated SOC, and NT only increased the SOC in the microaggregates. However, the contents of microbial biomass and GRSPs within bulk soil and different aggregate fractions were higher in NT and RT than in CT. Among the four aggregate fractions, greater values of SOC, microbial biomass and easily extractable GRSP (EEGRSP) were found in microaggregates and macroaggregates, respectively; while the total GRSP (TGRSP) was distributed equally among aggregate fractions. Structural equation modelling revealed that SOC, microbial biomass, and GRSPs accounted for 79% of the variation in soil aggregation. Soil organic carbon influenced aggregate stability indirectly through the effects on MBC and MBN. Microbial biomass and glomalin were more important driving factors for aggregate stability in the RT and NT systems. Our results suggest that conservation tillage (RT and NT) is beneficial for soil structure due to its positive effects on aggregation processes in black soil region of Northeast China.

Spatial patterns of soil biological and physical properties in a ridge tilled and a ploughed Luvisol

The present study was conducted to determine the spatial heterogeneity of bulk density, soil moisture, inorganic N, microbial biomass C, and microbial biomass N in the ridge tillage system of Turiel compared to conventional mouldboard ploughing on three sampling dates in May, July, and August. The soil sampling was carried out under vegetation representing the ridge in a high spatial resolution down the soil profile. Bulk density increased with depth and ranged from 1.3 g cm −3 at 10 cm depth to 1.6 g cm −3 at 35 cm in ploughed plots and from 1.0 g m −3 at 5 cm to 1.4 g m −3 at 35 cm in the ridges. In the ploughed plots, the contents of microbial biomass C and microbial biomass N remained roughly constant at 215 and 33 μg g −1 soil, respectively, throughout the experimental period. The microbial biomass C/N ratio varied in a small range around 6.4. In the ridged plots, the contents of microbial biomass C and microbial biomass N were 5% and 6% higher compared to the ploughed plots. Highest microbial biomass C contents of roughly 300 μg g −1 soil were always measured in the crowns in July. The lowest contents of microbial biomass C of 85–137 μg g −1 soil were measured in the furrows. The ridges showed strong spatial heterogeneity in bulk density, soil water content, inorganic nitrogen and microbial biomass.

CO 2 evolution from a ridge tilled and a mouldboard ploughed Luvisol in the field

This field study was initiated to measure soil CO 2 evolution of the Turiel ridge tillage system under faba bean ( Vicia faba L.) compared with mouldboard ploughing. The CO 2–C measurements were done in situ with a transportable infrared gas analyzer at different positions on the ridges and furrows and on mouldboard plough plots with and without vegetation, respectively. The CO 2 evolution at different ridge positions reflected a ridge pattern with a CO 2–C evolution in the order crown > shoulder > furrow. On a hectare basis the mouldboard ploughed soil evolved 0.11 t more CO 2–C ha −1 than ridges, and the plots with vegetation evolved 0.58 t more CO 2–C ha −1 than the plots without vegetation during the investigation period of 57 days. At higher air temperatures the soil temperature tended to be higher on ploughed plots compared to ridges. The CO 2 evolution on the planted plots decreased with time, reflecting the decreasing physiological activity of the plant roots. Overall, despite a high degree of soil disturbance, the amount of CO 2 evolved from the ridge tilled soil was lower compared to mouldboard plough tillage, probably reflecting less favorable conditions for soil microorganisms in the ridges compared to the ploughed soil.

Land Use Effects on Runoff and Water Quality on an Eastern Arkansas Soil Under Simulated Rainfall

ABSTRACT Over the past century, a significant proportion of the native grasslands that once occupied much of the middle third of the United States have been converted to cultivated agriculture, causing short- and long-term variations in soil physical and hydraulic properties that influence runoff-infiltration partitioning and runoff water quality. Eastern Arkansas is highly agriculturally productive when irrigated. However, the long history of irrigated agriculture and more recent shifts in rainfall patterns during the growing season have resulted in regional groundwater aquifer depletion with minimal regional recharge. The objective of this study was to evaluate the effects of land use on soil physical properties, runoff-infiltration partitioning, and runoff water quality on a typical agricultural soil in the Mississippi River Delta region of eastern Arkansas. Small-plot rainfall simulations were conducted on an Immanuel silt loam, (fine-silty, mixed, active, thermic, Oxyaquic Glossudalf) in plots (1.5 × 2 m) under native tallgrass prairie (PR) and two cultivated agroecosystems, ridge-tillage (RT), and conventional-tillage (CN). Residue cover was greatest in the PR and lowest in the CN system and differed significantly (p < 0.05) among all three land uses. However, runoff from the two agroecosystems did not differ, averaging 87% of the total amount of water applied, but both were significantly greater (p < 0.05) than that from the PR system, which averaged 62% of the total amount of water applied. Runoff turbidity and suspended solid concentration and load were greater (p < 0.05) from the CN than from the RT or PR systems. The CN system also had the greatest (p < 0.05) total P concentration and load, but the RT system produced runoff with the greatest (p < 0.05) soluble reactive P concentration and load of the three systems. Results indicate that land use and the degree of soil disturbance significantly affects runoff-infiltration partitioning and runoff water quality on this typical eastern Arkansas agricultural soil. Should results prove consistent on other regional soils, further depletion of local aquifers and degradation of surface water quality will likely continue if more sustainable agricultural practices are not increased.

Modeling soil carbon sequestration in agricultural lands of Mali

Agriculture in sub-Saharan Africa is a low-input low-output system primarily for subsistence. Some of these areas are becoming less able to feed the people because of land degradation and erosion. The aim of this study is to characterize the potential for increasing levels of soil carbon for improving soil quality and carbon sequestration. A combination of high- and low-resolution imagery was used to develop a land use classification for an area of 64 km 2 near Omarobougou, Mali. Field sizes were generally small (10–50 ha), and the primary cultivation systems are conventional tillage and ridge tillage, where tillage is performed by a combination of hand tools and animal-drawn plows. Based on land use classification, climate variables, soil texture, in situ soil carbon concentrations, and crop growth characteristics, the EPIC-Century model was used to project the amounts of soil carbon sequestered for the region. Under the usual management practices in Mali, mean crop yield reported (1985–2000) for maize is 1.53 T ha −1, cotton is 1.2 T ha −1, millet is 0.95 T ha −1, and for sorghum is 0.95 T ha −1. Year-to-year variations can be attributed to primarily rainfall, the amount of plant available water, and the amount of fertilizer applied. Under continuous conventional cultivation, with minimal fertilization and no residue management, the soil top layer was continuously lost due to erosion, losing between 1.1 and 1.7 Mg C ha −1 over 25 years. The model projections suggest that soil erosion is controlled and that soil carbon sequestration is enhanced with a ridge tillage system, because of increased water infiltration. The combination of modeling with the land use classification was used to calculate that about 54 kg C ha −1 year −1 may be sequestered for the study area with ridge tillage, increased application of fertilizers, and residue management. This is about one-third the proposed rate used in large-scale estimates of carbon sequestration potential in West Africa, because of the mixture of land use practices.

Banded herbicide, rotary hoeing and cultivation effects on weed populations in ridge-tilled soybean

Can banded herbicide be eliminated in ridge-tilled soybean (Glycine max)? The effects of banded herbicide, rotary hoeing and cultivation on weed populations and soybean yield in a ridge-tillage system were tested on three farms in Iowa, USA in 1989 and 1990. In 1989, plots either had no herbicide or had herbicide banded in the row at planting in mid-May; all plots received two rotary hoeings and two cultivations. In 1990, treatments were banded herbicide with no rotary hoeing, banded herbicide with one rotary hoeing, and no herbicide with one or two rotary hoeings; all plots received two or three cultivations. In both years, over all weed species [primarily giant foxtail (Setaria faberi), Pennsylvania smartweed (Polygonum pensylvanicum) and redroot pigweed (Amaranthus retroflexus)], seedling emergence was highest in late May and early June, with few seedlings emerging after mid-June. Weed populations were highest in May and June, after which rotary hoeing and cultivation reduced weed numbers in all plots. There were no consistent differences among treatments in weed numbers in early August for the 2 years. In both years, there was no significant difference in soybean yield among treatments. Within-farm mean yields ranged from 2.26 to 3.01 Mg ha−1among farms in 1989 and from 2.07 to 2.93 Mg ha−1among farms in 1990. Ridge-tillage without herbicide was generally equivalent to ridge-tillage with banded herbicide, with respect to total number of weeds and number of broad-leaved weeds remaining in August after tillage, and to soybean yield.

The effect of autumn ridging and inter-row subsoiling on potato tuber yield and quality on a sandy soil in Denmark

Autumn ridging is a modified version of the ridge tillage system. Instead of setting up ridges during the growing season, they are established in autumn and left for the winter. Previous studies have documented positive effects of autumn ridging on potato yield and we hypothesized that subsoiling could enhance these effects. To determine the effect of autumn ridging and inter-row subsoiling on potato yield and quality a field experiment was conducted on sandy soil from 2001 to 2003. Autumn ridging resulted in an average total and marketable tuber yield of 25.6 and 9.2 t ha −1, which was not significantly different from the average total and marketable yield of 25.6 and 8.9 t ha −1 with ploughing. However, autumn ridging significantly reduced the incidence of black scurf from 2.5% to 2.2%. Inter-row subsoiling in the growing season significantly increased marketable potato tuber yield from 8.4 to 9.6 t ha −1 and reduced the occurrence of malformed potatoes from 9.3% to 7.5%, irrespective of tillage treatment and irrigation level. There was no significant interaction between autumn ridging and subsoiling. The beneficial effect of subsoiling on marketable yield was driven by a 48.5% increase in the dry year of 2001. Subsoiling reduced the incidence of common scab from 7.8% to 6.9% when irrigation was reduced. It is concluded that at least three factors may modify the effects of subsoiling: Soil water status in the growing season, precipitation immediately before and after the subsoiling operation, and crop growth stage at the time of subsoiling.

Influence of Residual and Fresh Subsurface Phosphorus Fertilizer Bands on Soil Phosphorus Profile Distribution and Maize Growth and Shoot Phosphorus Uptake

ABSTRACT A field study was conducted at Beresford, SD, to examine how residual fertilizer phosphorus (P) bands influenced the distribution of Bray-1 extractable P in the soil profile and maize (Zea mays L.) shoot growth and P uptake in a ridge-till system. Liquid ammonium polyphosphate (10-34-0) was injected each fall for three consecutive years in either one or two concentrated subsurface bands in a 5 × 5 cm configuration with respect to the planted seed at rates to provide either 0, 10, 20, or 40 kg P/ha. Soil samples were removed once in the spring before planting with a rectangular block sampler along a 30 cm transect perpendicular to the ridge row to a depth of 15 cm after the third year of the P application. The large sample was separated into eight 7.5 × 7.5 cm × 7.5 cm block sections. Soil was analyzed for Bray-1-extractable orthophosphate-P in each of the sample blocks, composited for increasingly greater soil volumes, and compared with shoot growth and P uptake at the sixth and twelfth leaf and silking stage of growth. Applied-P rate had a strong effect on Bray-1-P levels, increasing them from 7.5 to 195.1 mg P/kg as P rate increased from 0 to 40 kg P/ha. The locations of the previously applied P bands were highly variable in the sampling profile. Coefficients of variation (c.v.) for Bray-1-P levels varied from 1.9 to 141.4 for sampling-block locations and increased as P rate increased. This result indicated that, within treatment replication, there was little consistency with fertilizer P-band placement with respect to the planted seed, and the variability increased with higher P applications. Applied-P rate influenced shoot dry weight, shoot P concentration, and shoot P uptake in the sixth leaf and twelfth leaf growth stages only. The band number had no influence on these parameters. When increasingly larger volumes were considered to improve the accuracy of sampling position with the predictability of the Bray-1 P levels and shoot parameters, the smallest soil volume and sampling position close to the planted seed was as accurate a predictor of shoot parameter responses as the Bray-1 P levels derived from soil composites of larger sampling volumes.

Effects of fertilizer placement on solute leaching under ridge tillage and no tillage

Elevated nitrate concentrations in ground water can be a problem in agricultural areas, especially where soils are sandy. Tillage operations, such as ridge tillage (RT) and no tillage (NT) can reduce runoff and erosion but leaching of soluble nutrients could adversely impact groundwater. In a 2-year study, Br was used to trace the effects of fertilizer placement on solute movement under corn ( Zea mays L.) in RT and NT systems on a Monmouth fine sandy loam (Typic Hapludult) in Maryland. Treatments included 120 kg ha −1 of Br − or NO 3 −-N applied in a narrow band near the ridge top (RT-RA) or in the furrow (RT-FA) with ridge tillage, or in the inter-row with NT. Two-dimensional arrays of tensiometers and suction lysimeters were used to follow the movement of water and solutes during and after the corn-growing season. Tillage and fertilizer placement did not significantly affect N uptake when averaged across years. A pronounced argillic horizon beginning at 60 cm depth caused lateral movement of Br. It appears that Br leaching in RT-RA increased slightly due to the crop canopy funneling rain towards the ridge top. Therefore, when fertilizer is applied near the row, rain occurring after full corn canopy may cause greater solute leaching in RT-RA compared to other treatments. Rain during the beginning of the growing season or after harvest caused less leaching in RT-RA. Corn yield could be maximized and N leaching minimized by applying fertilizer to the upper portion of the ridge in RT.