Conventionally-tilled Plots Research Articles

Infrared-based analysis of organic matter composition in liquid and solid runoff fractions collected during a single erosion event

Heavy rain events can cause soil material to be widely transported by surface runoff in arable soil landscapes. While soils of the eroded hilltop and backslope areas are affected by a loss of material, soil properties in deposition areas are affected by sedimentation of particulate and dissolved mineral and organic substances. During the event, the composition of mineral and organic matter (OM) fractions changes dynamically with runoff velocity. However, changes in OM composition during runoff have mostly been neglected. The objective was to identify changes of OM composition of runoff fractions with time and flow velocity during a single rainfall-runoff event. By the comparison of runoff from a conventionally-tilled (CT) plot and a no-till (NT) plot, we aimed at discussing process-based explanations for dynamic OM composition in runoff. Surface runoff was collected from CT and NT plots at the toe-slope of an experimental hillslope. Time-dependent runoff samples were compared with cumulative bulk samples obtained by Coshocton wheels and separated in a coarser sediment (sed>63 µm) and a finer fraction of < 63 µm-sized particles plus dissolved OM (<63 µm&diss). The OM composition was determined with Fourier transform infrared (FTIR) spectroscopy. It was found to change with runoff volume due to contact with litter (NT) or soil minerals (CT) mainly for finer fractions from both CT and NT plots. Even during a single runoff event, the OM mass and composition in runoff changes characteristically. The OM composition dynamics was dominated by OMcat/C-O-C ratios in runoff from CT and by C-H/CO ratios in runoff from NT due to contact with soil minerals (CT) and litter (NT). The time-dependent collection schemes suggested that OM composition in runoff reflected the surface properties and could help to further improve explanations for spatial distribution of OM-related soil properties such as the potential wettability in arable soil landscapes.

Long-term adoption of bed planted conservation agriculture based maize/cotton-wheat system enhances soil organic carbon stabilization within aggregates in the indo-gangetic plains

Sustainability of contemporary crop establishment and management practices is questioned due to soil degradation, higher carbon emission and declining soil productivity. Hence, this study was conducted to address the impacts of conservation agriculture (CA) practices like permanent broad beds (PBB), permanent narrow beds (PNB) and zero tilled flat beds (ZT) with residue retention on soil organic carbon (SOC) protection within aggregates in the Indo-Gangetic Plains (IGP). Compared to conventionally tilled (CT) plots, the total SOC content was ∼27%–33% higher in the CA plots on equivalent mass basis. The soil physical properties, such as soil aggregation and mean weight diameter were considerably improved under the CA practices. The macroaggregates were ∼41, 37% and 27% higher in the PBB with residue (PBB + R), PNB with residue (PNB + R) and ZT with residue (ZT + R) plots (CA plots), respectively, than the CT plots in the surface soil (0–15 cm). The plots under PBB + R had ∼31% higher microaggregates within macroaggregates than the CT plots (24.4 g 100 g−1) soil. An increase in SOC content by ∼72, 55% and 69% was observed in the PBB + R, PNB + R and ZT + R plots over the CT plots in microaggregates within macroaggregates (3.02 Mg ha−1). However, plots under PBB + R, PNB + R and ZT + R had only ∼11, 3% and 23% more SOC within silt + clay fraction, respectively, than CT plots (5.85 Mg ha−1). Thus, SOC stabilization within microaggregates inside macroaggregates was the major mechanism, and not the chemical stabilization within silt + clay, of C sequestration under CA. As aggregate-associated carbon is an ecosystem property that strongly affects organic carbon stabilization, water holding capacity and resistance to erosion, growing maize/cotton–wheat system under PBB + R practice is a viable option for carbon sequestration in the IGP and similar agro-ecologies.

Four years of conservation agriculture affects topsoil aggregate-associated 15nitrogen but not the 15nitrogen use efficiency by wheat in a semi-arid climate

Available results on the evaluation of nitrogen (N) use efficiency in conservation agriculture (CA) are inconsistent and studies that cover all three components of CA are sparse, especially in tropical agro-ecosystems. Hence, CA effects on variations in total soil N (TSN) and aggregate-associated 15N on a sandy loam soil were evaluated after 15N urea (~5% atom excess) application at 120 kg ha−1 to wheat in the fourth year of an experiment in the Indo-Gangetic Plains (IGP). The cropping system during 2008–2011 was cotton (Gossypium hirsutum)-wheat (Triticum aestivum), that was changed to maize (Zea mays)-wheat in 2011–2012. Results revealed that plots under zero tillage with residue retention of both crops (ZT + R) had better topsoil (0–5 cm layer) aggregation and higher residual 15N in soils than conventionally tilled (CT) plots. The ZT + R plots also had higher macro-aggregates (0.25–8 mm) with less silt + clay sized particles than the CT plots in the 5–15 cm soil layer. Furthermore, both tillage and residue management had significant effects on TSN and aggregate-associated N stocks. The plots under ZT + R had ~9% higher TSN in topsoil than the CT plots and the ZT and ZT + R plots had about 48 and 34% higher large macro-aggregate associated N stocks than CT and CT + R plots, respectively. However, the potential N-mineralization data of the macro-aggregates of ZT + R (CA) and CT plots were similar. In addition, the fertilizer 15N use efficiency, the residual fertilizer 15N in soil (0–45 cm layer) and the calculated unaccounted fertilizer 15N data of both CA and CT plots were also similar after the fourth year of cultivation. In summary, although CA (ZT + R) adoption had better soil aggregation and with more TSN accumulation within macro-aggregates, it could not affect the fertilizer 15N use efficiency within a short period (4 years). Thus, with a short-term adoption of CA, fertilizer-N dose may not be reduced in a sandy loam soil of the IGP and similar agro-ecosystems.

Transition from Conventional to No-Tillage in Poorly Drained Clay

No-tillage has been recognized as one of the best tillage practices in preventing soil from erosion and sequestering carbon. However, agricultural producers have seen negative results in clay soils (e.g. soil compaction and poor crop yield) immediately after converting conventional tillage to no-tillage. A three-year on-farm study was conducted to investigate two different transition strategies for switching from conventional tillage to no-tillage in poorly drained, heavy clay soils. Field plots were established in Manitoba, Canada in 2006, 2007, and 2008. The corresponding crops were canola, wheat, and barley. The transition strategies used were planting alfalfa ahead of time before no-tillage and performing subsoiling before no-tillage. Conventional tillage was also included as a control. Field measurements were performed on residue cover, soil properties (moisture content, bulk density, and cone index), and plant performance (plant biomass and grain yields). Results showed that no-tillage plots on alfalfa had over 90% residue cover, and the residue covers of subsoiling plots were higher than the conventionally-tilled plots. As compared with the conventional tillage, the no-tillage soil established on the alfalfa field had lower moisture content and higher cone index, which adversely affected the plant biomass and grain yields; whereas the no-tillage soil established after subsoiling had lower soil bulk density and cone index, which favored better plant biomass and grain yields.

Assessing soil particle-size distribution on experimental plots with similar texture under different management systems using multifractal parameters

Soil particle-size distribution (PSD) is a fundamental soil physical attribute with dominant influence on many other soil properties. Laser diffraction combined with multifractal analyses have proven to be useful to obtain precise information from PSDs. The aim of this work was to assess similitude or difference of PSDs sampled on plots of an experimental field and belonging to the same textural class using multifractal parameters. The field experiment consisted of two tillage treatments and two cropping systems. It was conducted following a randomized complete split-block design with four replications on a Humic Dystrudept. Tillage treatments were conventional tillage (CT) and no tillage (NT) while crop rotations were ryegrass–sorghum (RS) and ryegrass–corn (RC). Particle-size distribution analysis by the sieve–pipette and by laser diffraction corroborate that all the samples were assigned to the same textural class. Singularity spectra f( α) and Rényi spectra, D q , showed that multifractal distribution was a suitable model for PSDs obtained by laser diffraction. However, in the range of moments − 10 < q < 10, the r 2 values for the linear fits leading to a Rényi spectrum, D q , were higher than those for the singularity spectrum, suggesting the former was better defined than the latter. No significant differences in multifractal parameters were found between plots with contrasted crop rotation, RS and RC. In contrast, Hölder exponent of order zero ( α 0) and several parameters derived from the left branch of both, the f( α) and the D q spectra, were significantly different between CT and NT treatments. No effects of mixing by cultivation were detected in our work, so that differences in PSDs between no-tilled and conventionally-tilled plots were simply attributed to patchiness and variation on the experimental field. Multifractal analysis of PSDs measured by laser diffraction provides further insight in verifying patterns of between plot soil texture variations (i.e. randomness or trends) in completely randomized block designs.

Quickbird satellite and ground-based multispectral data correlations with agronomic parameters of irrigated maize grown in small plots

Satellite remote sensing has not been practical for agronomic research conducted using small plots due to spatial resolution issues. The objectives were to determine, (1) the potential use of QuickBird high resolution multispectral images for estimating available nitrogen (N) at planting, leaf N content at the tassel (VT) growth stage, and yield (biomass and grain) of irrigated maize (Zea mays L.) grown in research size plots and (2), if image digital number (DN) values were adequate for assessing these agronomic parameters. Conventionally-tilled plots 21.3 m × 21.6 m, 10.7 m × 43.3 m, and 10.7 m × 21.6 m were used. QuickBird images (2.5 m pixel resolution) were obtained at the VT growth stage for two growing seasons along with ground-based reflectance for one growing season. Multispectral data [blue (450–520), green (520–600), red (630–690), and near-infrared (760–900 nm)] was acquired by both sources. Relative green (G) waveband DN had the highest correlations with available N at planting (r2 = 0.91), relative grain yield (r2 = 0.81) and relative total biomass (r2 = 0.59) than any of the other indices investigated. Relative spectral indices containing G and near-infrared (NIR) wavebands, i.e., the green normalised difference vegetation index (GNDVI), the NIR/G ratio and the chlorophyll index ((NIR/G)−1) produced good correlations with leaf N content at VT (r2 > 0.7). Regression parameters (slopes and intercepts) of the normalised (NIR/G)−1 index calculated from satellite DN values and ground-based reflectance versus leaf N content were not significantly different (α = 0.01). Results indicate that QuickBird multispectral images show promise for estimating agronomic parameters from small plot research. Additional research is required to expand the results to more maize growth stages and other crops.

Root abundance of maize in conventionally-tilled and zero-tilled soils of Argentina

Maize root growth is negatively affected by compacted layers in the surface (e.g. agricultural traffic) and subsoil layers (e.g. claypans). Both kinds of soil mechanical impedances often coexist in maize fields, but the combined effects on root growth have seldom been studied. Soil physical properties and maize root abundance were determined in three different soils of the Rolling Pampa of Argentina, in conventionally-tilled (CT) and zero-tilled (ZT) fields cultivated with maize. In the soil with a light Bt horizon (loamy Typic Argiudoll, Chivilcoy site), induced plough pans were detected in CT plots at a depth of 0-0.12 m through significant increases in bulk density (1.15 to 1.27 Mg m-3) and cone (tip angle of 60 º) penetrometer resistance (7.18 to 9.37 MPa in summer from ZT to CT, respectively). This caused a reduction in maize root abundance of 40-80 % in CT compared to ZT plots below the induced pans. Two of the studied soils had hard-structured Bt horizons (clay pans), but in only one of them (silty clay loam Abruptic Argiudoll, Villa Lía site) the expected penetrometer resistance increases (up to 9 MPa) were observed with depth. In the other clay pan soil (silty clay loam Vertic Argiudoll, Pérez Millán site), penetrometer resistance did not increase with depth but reached 14.5 MPa at 0.075 and 0.2 m depth in CT and ZT plots, respectively. However, maize root abundance was stratified in the first 0.2 m at the Villa Lía and Pérez Millán sites. There, the hard Bt horizons did not represent an absolute but a relative mechanical impedance to maize roots, by the observed root clumping through desiccation cracks.

Effects of living mulches or residue amendments on soil microbial properties in direct seeded cropping systems of Madagascar

There is growing recognition for the need to study the impact of agricultural land uses on biological and biochemical properties of soils. In Madagascar, cropping systems based on direct seeding with permanent vegetation cover provide a new means for sustainable agriculture to protect the environment and make the most of natural resources. This study assessed the effects of different direct seeding mulch-based cropping systems on soil microbial biomass and activities. The soil was andic Dystrustept. Samples of the soil were taken from 0 to 5 cm soil layer of three direct seeding mulch-based cropping systems (DMC using crop residues and living mulches). The samples were compared with samples from conventionally tilled plots (CT) and natural fallows (NF). The field experiments were carried out over a 12-year-period and two types of amendment were applied once a year at sowing, farmyard manure (FYM) and farmyard manure combined with an NPK chemical fertilizer. The C and N content, microbial basal respiration and biomass and β-glucosidase, urease and acid phosphatase activities were determined. The results showed that there was no interaction between soil management strategies and the use of fertilizer. Furthermore, the fertilizer did not affect the soil C and N content or the acid phosphatase and urease activities. Farmyard manure with added NPK had a significantly greater effect than farmyard manure on its own, increasing the microbial biomass, soil respiration and β-glucosidase activity up to 26%, 52% and 20%, respectively but there was no significant difference between natural fallows and direct seeding mulch-based cropping systems. However, conventional tillage showed a significantly lower soil microbial biomass, C content, microbial respiration and urease activity than natural fallows. The results for direct seeding mulch-based systems varied according to the microbial activities measured. However, soil β-glucosidase and acid phosphatase activities were significantly higher for the direct seeding mulch-based systems using crop residues than for the direct seeding mulch-based systems using living mulches. Direct seeding mulch-based systems with Desmodium uncinatum living mulch had significantly lower microbial biomass and respiration than the other direct seeding mulch-based systems. There was less evidence of change in the soil between natural fallow and direct seeding mulch-based systems but a higher build-up of some microbial properties was obtained for direct seeding mulch-based systems soil than in conventionally tilled soils and natural fallow.

287 IMPROVED PERFORMANCE OF SHRUNKEN-2 SWEET CORN USING TRICHODERM HARZIANUM AS A BIOPROTECTANT

A strain of the biocontrol fungus Trichoderma harzianum was tested for effectiveness in improving the performance of sh2 sweet corn using a variety of delivery methods. In greenhouse trials, Trichoderma seed treatment reduced the proportion of weak plants (unlikely to make a marketable ear) from 40% to 10%. This is evidence that the characteristically uneven stand establishment of supersweet corn should be overcome by using Trichoderma. In field trials, Trichoderma and Gliocladium (a related fungus) were inoculated as a seed treatment without fungicide in spring-tilled plots. Yields of uninoculated controls were 2.2, Gliocladium-treated were 2.6, and Trichoderma -treated were 3.6 T/ac. Delivering the same lines of fungus in the fall to a rye cover crop resulted in high populations the following spring. The cover crop was killed and fungicide-treated seed of `Zenith' sweet corn was planted without tillage. Yield with Trichoderma was 4.0, with Gliocladium was 3.7, and uninoculated was 2.4 T/at. The uninoculated, conventionally-tilled plots also yielded 4 T/at. Thus the beneficial fungi overcame the inhibition caused by no-till. Trichoderma was delivered effectively both as a seed treatment and on a winter cover crop to improve stand uniformity and overall yield.

Root growth of maize in a compacted gravelly tropical alfisol as affected by rotation with a woody perennial

Abstract The objective of this experiment was to evaluate the effects of growing a deep-rooting perennial on the root system development of a subsequent crop with low root penetrating ability. These effects were measured on a gravelly Alfisol with a compacted subsoil horizon for three tillage methods (zero tillage, conventional tillage and reduced tillage, consisting of chiseling in the row zone once a year) and two cropping sequences (pigeon pea-maize and continuous maize). The root development was related to changes in soil physical and chemical properties. At all times overall root growth was in the order of zero tillage > reduced tillage > conventional tillage. Among zero-tilled plots, maize root growth in plots sown to a pigeon pea-maize sequence was greater than in plots sown to continuous maize. Macroporosity of the gravel layer, measured as soil water content at 0 kPa in the 500–600 mm depth, was not affected by cropping sequence. Among tillage systems, soil water content at 0 kPa was 18.9, 11.8 and 13.9% on a volume basis for zero-tilled, reduced-tilled and conventionally-tilled plots, respectively. Soil physical properties above the gravel layer were improved in the order of zero tillage > reduced tillage > conventional tillage. Among zero-tilled plots, however, the pigeon pea-maize sequence improved soil physical properties more than continuous maize did. Mean seasonal soil temperature at 50 mm depth, measured at 1400 h during the major growing season, was 32.8 and 34.7°C in zero-tilled plots sown to a pigeon pea-maize sequence and continuous maize, respectively. At the same time mean seasonal temperature was 33.8, 35.5, and 39.7°C in zero-tilled, reduced-tilled and conventionally-tilled plots. In relation to continuous maize, sowing of pigeon pea prior to maize increased levels of organic carbon, exchangeable Ca, Mg and K and cation exchange capacity. Grain yield in plots sown to a pigeon pea-maize sequence was greater than in plots sown to continuous maize. Among tillage systems zero-tilled and reduced-tilled plots outyielded conventionally-tilled plots.

Field Corn, Black Cutworm Planting-Time and Rescue Treatments, 1985

Abstract A field evaluation of registered and experimental insecticides to control artificial infestations of black cutworm larvae under 2 tillage systems (fall plow, spring disk; no-till) was conducted in Champaign, IL. Corn (Pioneer 3747) was planted in 30-inch rows at a plant population of 26100 on May 9. Sixty plots (32 plots in no-till and 28 plots in conventional till) were established by erecting 6-inch high aluminum barriers over the corn rows immediately after planting. Each plot measured 56 × 7 inches and enclosed an average of 7 corn seeds. Each plot was infested with laboratory-reared black cutworms (fourth to fifth instar) as follows: 2 larvae each on 12 and 17 May and one larva each on 21, 24, 28, 31 May and 4 Jun. All insecticides except the Lorsban 4E rescue treatment were applied on 13 May using either a CO2 sprayer equipped with a 1-nozzle wand for the liquids (Spraying Systems no. 80015E even flat fan nozzle, 3.9 ft/sec, 20 psi, 20 gal water/acre) or a Noble metering unit attached to a bicycle-wheeled applicator for the granules. In the conventionally tilled plots, Ambush, Pydrin, one of the Pounce treatments, and a pre-emergence application of Lorsban were very lightly incorporated into the upper 1 inch of soil with a hand cultivator. In both tillage experiments, the Lorsban 4E rescue treatments were applied when insect damage was first noted on 18 May (corn in spike stage) and existing cut plants were marked at application. In each tillage experiment, treatments were arranged in a randomized complete block design with 4 replications. Seedlings were assessed for cutting damage daily until 17 Jun.

Effects of zero and conventional tillage on the length and irregularity of elongated pores in a clay loam soil under viticulture

Total porosity and width, length and irregularity of elongated pores from thin sections, prepared from undisturbed Ap horizon samples taken from a zero versus conventional-tillage field experiment, were analysed by means of a Quantimet 720 System 23 image analysing computer. Both total porosity and elongated pore area were significantly higher in conventionally-tilled plots. On the contrary, both the total number of pores and the proportion of elongated pores were significantly higher in no-tilled plots. Thus, zero tillage reduced the size of pores. Conventional tillage caused an increase in the length of a few large, elongated pores which also showed very strong irregularity. In samples from no-tilled plots the total length of elongated pores was smaller, but these pores were more numerous and more regular than in samples from conventionally-tilled plots. Consequently, soil conditions for root growth were better.