Tillage Management Research Articles

Chemical diversity and molecular signature of soil humic fractions used as proxies of soil quality under contrasted tillage management

Increasing food production while avoiding the progressive degradation of agricultural soils has become one of the major challenges at a global level. In consequence, the development of sustainable tillage methodologies or cultivation strategies is an important subject of current research. In fact, it has been observed that the implementation of reduced tillage (RT) vs. traditional tillage (TT) in the long term not only improves soil physicochemical properties but also global soil quality in terms of soil health. In particular, the increase of the soil organic carbon (SOC) content under RT conditions is one of the most important factors, but there is little information about the chemical composition and humification level of this carbon, and thus about its persistence at long-term. This is of particular importance considering the policies of carbon sequestration and climate change mitigation, such as the “4 per 1000” initiative. In this study, molecular-level characterization of the humic acid (HA) and fulvic acid (FA) fractions isolated from a soil after 19 years under RT and TT practices was carried out. This study would provide objective descriptors of the impact of these two tillage practices in the chemical composition of the resulting SOC. With this purpose, the potential of Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS) for assessing changes in the molecular assemblages released from the humic fractions (HA and FA) was examined. The results showed enhanced diversity and chemical richness (expressed as number of molecular formulas) in the composition of SOC under RT. Different tillage-specific compound classes were associated with both tillage practices. As a whole, the humic fraction showed a higher proportion of molecular formulas for lipid and hydroaromatic families in the case of RT compared to TT, while the same fraction under TT showed a greater richness of oxidized protein-derived formulas than RT. In the case of FAs, a similar pattern was observed for hydroaromatic and protein-derived formulas, but the proportion of molecular formulas assigned to unsaturated lipids was higher in TT than in RT. In addition, increased number of formulas for aromatic and condensed aromatic compounds was observed in FAs under TT respect to RT.

Role of tillage and straw management on SOC sequestration: a sustainable approach of soil conservation

Role of tillage and straw management on SOC sequestration: a sustainable approach of soil conservation

Soil Physical Properties, Carbon dioxide Emissions and Their Relationships under Different Management Systems in Semi-arid Region of Eastern Tunisia

ABSTRACT In agricultural systems, soil carbon dioxide emissions and physical properties are thought to depend largely on management practices. This field study was carried out in a semi-arid region of eastern Tunisia to evaluate the effects of tillage management on soil carbon dioxide emissions and related physical properties; bulk density (BD), penetration resistance (PR), total porosity (TP) and air-filled porosity (AFP). Tillage management treatments included plowing with a moldboard plow or a disk plow to different depths, described here as shallow (10 cm), medium (15 cm) and deep (25 cm). No-tillage was also considered as a control plot. Correlation analysis was used to explore how soil carbon dioxide emissions (CO2) were related to the other studied properties. The results showed higher carbon dioxide (CO2) emissions (p < .05) from tilled soil compared to no-till (NT), regardless of the tillage management. No significant differences in carbon dioxide (CO2) emissions were found between moldboard and disk plow tillage at the same tillage depth. Soil carbon dioxide release was the highest after deep tillage (moldboard = 0.101 t ha−1 and disk plow = 0.107 t ha−1) suggesting that deeper tillage to 25 cm promoted higher carbon dioxide (CO2) emissions. Significant differences with tillage were observed in bulk density (BD) and penetration resistance (PR) compared to no-tillage. Correlations of carbon dioxide emissions to soil physical properties across all the tillage treatments indicated significant negative relationships between carbon dioxide (CO2) emissions and soil bulk density (BD) and penetration resistance (PR) and significant positive relationships between carbon dioxide (CO2) and total porosity (TP) and air-filled porosity (WFP) suggesting that these soil attributes are important controlling factors of carbon dioxide (CO2) emissions.

Soil Bacterial Community Diversity and Composition as Affected by Tillage Intensity Treatments in Corn-Soybean Production Systems

Our understanding on the effects of tillage intensity on the soil microbial community structure and composition in crop production systems are limited. This study evaluated the soil microbial community composition and diversity under different tillage management systems in an effort to identify management practices that effectively support sustainable agriculture. We report results from a three-year study to determine the effects on changes in soil microbial diversity and composition from four tillage intensity treatments and two residue management treatments in a corn-soybean production system using Illumina high-throughput sequencing of 16S rRNA genes. Soil samples were collected from tillage treatments at locations in the Southern Coastal Plain (Verona, MS, USA) and Southern Mississippi River Alluvium (Stoneville, MS, USA) for soil analysis and bacterial community characterization. Our results indicated that different tillage intensity treatments differentially changed the relative abundances of bacterial phyla. The Mantel test of correlations indicated that differences among bacterial community composition were significantly influenced by tillage regime (rM = 0.39, p ≤ 0.0001). Simpson’s reciprocal diversity index indicated greater bacterial diversity with reduction in tillage intensity for each year and study location. For both study sites, differences in tillage intensity had significant influence on the abundance of Proteobacteria. The shift in the soil bacterial community composition under different tillage systems was strongly correlated to changes in labile carbon pool in the system and how it affected the microbial metabolism. This study indicates that soil management through tillage intensity regime had a profound influence on diversity and composition of soil bacterial communities in a corn-soybean production system.

Plant residue chemical quality modulates the soil microbial response related to decomposition and soil organic carbon and nitrogen stabilization in a rainfed Mediterranean agroecosystem

Soils play a major role in the global carbon cycle and are crucial to the management of climate change. Changes in plant cover derived from different agricultural practices induce variations in the quality of plant residue inputs and in the soil microbial community structure and activity, which may enhance the storage and protection of organic carbon (OC) and nitrogen (N) within aggregates. The aim of this study was to assess how differences in the chemical composition of plant residues in combination with tillage management practices affect the local microbial community activity and structure, and subsequent soil aggregation and OC and N dynamics in an organic, rainfed almond (Prunus dulcis Mill.) orchard. In the laboratory, three types of plant residue (shoots, roots, and the combination of both) coming from different species belonging to each agricultural practice (reduced tillage, reduced tillage plus green manure, reduced tillage plus organic manure, and no-tillage) were mixed with their respective soils and the CO2 released was measured over 243 days at 60% WHC and 28 °C. Water-stable aggregates (including microaggregates within macroaggregates), enzymatic activities related to carbon (dehydrogenase and β-glucosidase) and N (urease) cycling, and the microbial biomass and community structure through phospholipid fatty acid analysis, were measured at the end of the incubation period. Our results indicate that the chemical composition of plant residues controls the microbial community response, mediating decomposition and the incorporation of OC and N in stable aggregates. Therefore, the incorporation of labile and N-rich plant residues into the soil by reduced tillage is recommended since mixing roots and shoots from green manure increased the formation of free micro-aggregates and improved OC and N stabilization in our semiarid agroecosystem.

Impacts of 25-year rotation and tillage management on soil quality in a semi-arid tropical climate

Soil deterioration, yield decline and soil microbial activity reduction caused by banana (Musa × paradisiaca L.) monoculture is threatening the sustainability of banana production in China. Therefore, it is necessary to study the benefits of rotation on soil quality. This study aimed to assess the effects of rotation and tillage on soil properties in a banana plantation for 25 yr. Treatments consisted of three rotation methods (banana-pineapple, BA; banana-cowpea, BP; banana-rice, BR) and banana monoculture (CK) combined with two tillage intensities (no-tillage, NT; conventional tillage, CT). Soil samples were taken at depth of 0-40 cm in 2019-2020. In comparison with CK, BA and BR increased soil moisture, pH, total organic C and available P, but decreased soil bulk density. Microbial biomass C and N at booting stage were 46.1% and 39.2% higher in BA and BR than those in CK. Urease, dehydrogenase and β-glucosidase obtained a mean of 34.1% increase in BP and 23.8% increase in BR compared with BA. Higher total N, NO3-N, available K and macroaggregate were showed in NT compared with CT, whereas porosity was 24.8% lower in NT than in CT. CO2, N2O and CH4 emissions were in average around between one third and two fifth lower in no-tillage compared with conventional tillage. In general, rotations combined with no-tillage led to a positive effect on soil quality, as evidenced by increase of soil moisture, total N, microbial biomass C and urease and accompanying increase in banana yield. In order to sustain higher productivity, application of rotation and no-tillage is of considerable importance.

Evaluating soil physical quality indicators of a Vertisol as affected by different tillage practices under wheat-maize system in the North China Plain

Soil physical quality (SPQ) is an important parameter for crop growth. Tillage management is widely recognized to affect SPQ remarkably, but such an effect is complicated in Vertisols by shrinking and swelling soil structure. The objectives of this study were to (i) investigate how tillage practices affected SPQ as indicated by the S index, least limiting water range (LLWR) and water stress percentage (WSP); and (ii) determine the relationship between these SPQ indicators and crop yield. A 4-year field experiment, which was conducted in a Vertisol under wheat-maize rotation system in the North China Plain, consisted of four tillage treatments: no tillage (NT), rotary tillage (RT), subsoiling (SS), and deep ploughing (DP). Soil water retention curve (SWRC), soil shrinkage curve (SSC), penetration resistance (PR), and bulk density (BD) of the 0−10 and 10−20 cm layer were measured during wheat and maize seasons, and soil water content was continuously monitored in situ. The S index, LLWR and WSP were determined. Our results showed that SSCs were parallel to each other among four tillage treatments, indicating that tillage did not impact shrinkage capacity (P > 0.05). Relative to NT and RT treatments, the SS and DP treatments improved soil physical quality (higher S index and larger LLWR), particularly in the 10−20 cm layer. The S index presented a poor relation with wheat (P > 0.05) and maize yields (P > 0.05), while LLWR had a significant correlation with wheat yield (P < 0.05) but not with maize yield (P > 0.05). A new proposed SPQ indicator, WSP, is defined as the percentage of the period when the soil water content is above the field water capacity (waterlogging stress percentage, WLP) or below the wilting point (drought stress percentage, DSP) to the entire crop season period. The WLP presented a significantly negative relation with maize yield (P < 0.01) but not with wheat yield (P > 0.05), whereas the DSP had no relation with wheat and maize yield (P > 0.05). Moreover, the WSP was observed to be independent of the volume change in the Vertisol. Our results demonstrate that LLWR and WLP can be regarded as suitable indicators for evaluating SPQ in wheat and maize seasons, respectively, but the latter is more conveniently applied in a Vertisol.

Simulation of soil moisture dynamics, evapotranspiration, and water drainage of summer maize in response to different depths of subsoiling with RZWQM2

The contraindications of summer maize production, water resource shortages, and soil surface layer structural deterioration in the North China Plain (NCP) have become increasingly prominent. Subsoiling has been widely studied as a key tillage conservation technique. The objective of this experiment is to continue characterization of soil moisture dynamics, soil water consumption and drainage under different tillage management. In the present study, two subsoiling depths—35 cm (S35 + R15) and 40 cm (S40 + R15)—were examined and rotary tillage at 15 cm (R15) was used as the control. The volume moisture content of field soil was determined by Time Domain Reflectometry. The amount of water stored in the soil is calculated by the soil volumetric moisture content in the 0–130 cm soil profile cumulated. The amount of water stored in the soil at sowing and harvest time was used to calculate ET using the equation of water balance. The field experiment results were combined with the Root Zone Water Quality Model (RZWQM2) to calibrate and verify RZWQM2 using experimental data for summer maize in the growth period from 2017 to 2019. The results of the field trials showed that the soil water content (SWC) and evapotranspiration (ET) were increased by subsoiling compared to that by R15. RZWQM2 showed promising applicability in this scenario and successfully simulated the soil water dynamics caused by rainfall distribution during the years of treatment by R15, S35 + R15, and S40 + R15. The normalized root mean squared errors (nRMSE) for soil water storage (SWS) and ET were 11.31–19.65% and 11.99–16.57%, respectively. The corrected model was used to supplement the calculations of actual transpiration (AT), actual evaporation (AE), and water drainage. According to the calculations of the model, S35 + R15 and S40 + R15 treatments could effectively reduce the actual evaporation in the early growth period and maintain high transpiration in the middle and late growth periods. However, S40 + R15 treatment also resulted in a higher water drainage rate and greater cumulative water drainage. In terms of soil moisture dynamics, our findings suggest 35 cm to be the optimal depth for subsoiling in the NCP. Concurrently, the results suggest that increasing the depth of the subsoiling may lead to more water drainage.

Long-term crop rotation and different tillage practices alter soil organic matter composition and degradation

Conservation agriculture such as conservation tillage and crop rotation can alter soil organic matter (OM) storage and cycling. However, little is known about how these methods alter the molecular-level soil OM composition and turnover. We collected soil samples (0−10 cm) from a 37-year experiment with contrasting diversity crop rotations under conventional tillage and conservation tillage. Soil organic carbon concentrations, molecular-level OM composition and microbial biomass and community structure were measured. Soil organic carbon concentrations were similar between the two tillage practices, likely due to the balance between carbon loss via degradation and carbon gains through incorporation of crop residues in soil. We observed significant changes in soil OM composition between conventional tillage and conservation tillage despite similar soil organic carbon concentrations. Under long-term conservation tillage practice, lower suberin-derived compounds and higher lignin-derived compounds were observed. The degradation of cutin-, lignin-derived compounds and soil OM were lower under conservation tillage among most rotations. The changes in lignin-derived compounds and degradation were microbially driven and likely controlled by substrate utilization. In contrast, the differences in suberin-derived compounds were likely associated with crop residue-induced OM inputs and/or the differential introduction of OM (e.g. root materials) to the upper layer of soil due to conventional tillage vs. conservation tillage managements. These findings reveal that microbial degradation, OM inputs from crop residues and management-induced OM distribution in soil layers may alter agricultural soil OM composition. Additionally, we found that the differences in some specific groups of compounds between conventional tillage and conservation tillage were lower in crop rotations with higher diversity, highlighting the benefits of the interaction between diverse rotations and conservation tillage.

Soil carbon dynamics of no-till silage maize in ley systems

Converting grassland to arable cropping leads to reduced soil organic carbon (SOC) stocks and thereby affects soil and climate protection goals. However, in forage production systems, silage maize produces considerable amounts of herbage and metabolizable energy yields for ruminants. To answer the question whether using direct drilling, as a minimal soil invasive technique, is able to prevent SOC stock degradation without loss of herbage yield in ley-arable systems, a two-year field experiment was set up on a sandy loam soil in northern Germany. In pre-management, a 10-year-old grassland sward was eradicated with a glyphosate and then sown with silage maize with (i) direct drilling (no-till, NT); and (ii) by conventional mouldboard ploughing (conventional tillage, CT). Each treatment included a non-N-fertilized (N0) and a 90 kg N ha−1 year−1 fertilized (N1) treatment. All silage maize treatments were analyzed in terms of above- (ANPP) and belowground net primary production (BNPP) and potential C input in comparison with the grassland control (GC) during the two years after conversion to arable silage maize. Quantification of SOC stocks and origin of C derived from residual plant material was estimated by the determination of natural 13C isotope abundance. Long-term impacts on SOC of a proposed ley-arable system (three years of grassland followed by three years of silage maize) using NT and CT practices were predicted using a soil C model. Results showed that ANPP and BNPP did not differ (p > 0.05) between tillage treatments and the two experimental years. Fertilization increased ANPP only in the second year with a lower fraction of roots belowground in comparison with N0 (p < 0.05). According to the 13C signature the total of silage maize-derived C after two years was up to 2.5–3.2 t C ha−1 in both tillage treatments, of which ∼76% can be explained by the measured C inputs from plant residues. The NT treatment showed lower amounts of decay of previously sequestered C in the upper 10 cm during the two-year period after land use change to silage maize. However, long-term predictions revealed ongoing breakdown of soil C regardless of tillage management used for continuous silage maize after conversion from grassland. The insertion of a three-years grass phase followed by three years of silage maize established with NT techniques was able to maintain SOC stocks in the long-term.

Soil and Sweet Corn Quality Responses to Tillage, Residue, and Nitrogen Management in Southern Iran

Conservation tillage can drastically influence the environment by conserving soil due to enhancing soil structure and quality, thereby maintaining stable crop productivity and quality. To evaluate the effects of tillage practices, wheat residue management, and rate of nitrogen fertilization on soil and sweet corn quality, a 2-year (2014–2015) field study was conducted at the School of Agriculture farm, Shiraz University, Shiraz, Iran. Treatments consisted of three tillage systems including conventional (CT), reduced (RT), and no tillage (NT) as main plots, four N rates (0, 69, 138, and 207 kg N ha−1) as sub plots, and wheat residue management, removed versus retained, as sub–sub plots. Increasing N rates slightly increased ECe but not to the detrimental levels for crop or soil health. Soil pH was buffered due to the calcareous nature of the experimental soil. Soil organic carbon and total nitrogen were higher under RT and NT than CT, although the changes were considerably low. Soil bulk density was higher under NT treatment, which resulted in lower marketable yield after 2 years probably due to the limitations in nutrient uptake and N immobilization and applying high rates of N could reduce or eliminate N immobilization and limitations in nutrient uptake, resulted in comparable yield to CT. The higher N rates increased kernel protein content but reduced soluble solids of kernels (brix). Reduced tillage was slightly superior to the other two tillage practices in case of soil and kernel quality and marketable yield, while applying high N rate (207 kg N ha−1) to NT practice could compensate yield reduction during the transition from CT to NT practice.

Dynamics of Soil Organic Carbon and Labile Carbon Fractions in Soil Aggregates Affected by Different Tillage Managements

Our study aimed to provide a scientific basis for an appropriate tillage management of wheat-maize rotation system, which is beneficial to the sustainable development of agriculture in the fluvo-aquic soil areas in China. Four tillage treatments were investigated after maize harvest, including rotary tillage with straw returning (RT), deep ploughing with straw returning (DP), subsoiling with straw returning (SS), and no tillage with straw mulching (NT). We evaluated soil organic carbon (SOC), dissolved organic carbon (DOC), permanganate oxidizable carbon (POXC), microbial biomass carbon (MBC), and particulate organic carbon (POC) in bulk soil and soil aggregates with five particle sizes (&gt;5 mm, 5–2 mm, 2–1 mm, 1–0.25 mm, and &lt;0.25 mm) under different tillage managements. Results showed that compared with RT treatment, NT treatment not only increased soil aggregate stability, but also enhanced SOC, DOC, and POC contents, especially those in large size macroaggregates. DP treatment also showed positive effects on soil aggregate stability and labile carbon fractions (DOC and POXC). Consequently, we suggest that no tillage or deep ploughing, rather than rotary tillage, could be better tillage management considering carbon storage. Meanwhile, we implied that mass fractal dimension (Dm) and POXC could be effective indicators of soil quality, as affected by tillage managements.

Analysis of the use of tractors in different poles of agricultural development in Benin Republic

The deep assessment of agricultural mechanization inside developing countries could help for local action-taking. This study investigates the use of tractors between the poles of agricultural development (PAD) in Benin Republic. Using a multi-stage random sampling procedure and a questionnaire, 203 tractor users were surveyed in 43 municipalities distributed across the seven PADs of the country. Kruskal-Wallis tests were carried out to compare the different poles of agricultural development based on the mechanization level and tractor performances. Student-Newman-Keuls tests were used to structure the means of these variables. The results show a significant variation (P < 0.05) of the mechanization level between the PADs. Apart PAD1, all the poles use greater than 60 % manual equipment. Animal-drawn is most implemented in the northern part of the country (PAD1; 2 and 3). The use of tractors is lower over the country, and the PAD2 and PAD3 are the most users. From PAD4 to PAD7, the combination of manual tillage with animal power or tractor is not well represented, indicating manual tillage-based agriculture in these poles. In general, 53.20% of the users do not have a tractor parking and the repair center is quasi-absent (97.54 %). PAD2; 4 and 3 are most disc plow users. Mechanical sowing is more observed in PAD2 and 7 and absent in PAD1; 3 and 4. Moreover, the harvester is present in PAD2; 4; 6, and 7. On average, the highest mechanized area was 134.56 ha from PAD3, whereas, the lowest, 12.00 ha was found in PAD7. PAD7 spends more on plowing (47670 FCFA) than the other poles. The mechanized plowing is most slower in PAD7 (3.53 h/ha) while much faster at the PAD2 (1.96 h/ha). These results could help decision-makers for accurate actions taking to advocate for agricultural mechanization sectors in the country based on the weakness of each pole of agricultural development.

Integrated wheat-maize straw and tillage management strategies influence economic profit and carbon footprint in the Guanzhong Plain of China

Appropriate straw and tillage management strategies increase grain yields, and promote atmospheric carbon dioxide (CO2) mitigation through soil organic carbon (SOC) sequestration. However, little is known about economic parameters and carbon footprint (CF, defined as total greenhouse gases emission from the whole life cycle perspective) of intensive wheat (Triticum aestivum L.)-maize (Zea mays L.) double cropping production under different integrated strategies of straw-return and tillage. To quantify the differences of straw-return and tillage integrated strategies in economic parameters and carbon sustainability, a field experiment was established in 2008 in which six integrated strategies were evaluated: straw return of both maize and wheat (MR-WR), MR-WR with subsoiling to ~40 cm depth after maize harvest (MS-WR), single straw return of wheat (MN-WR), single straw return of maize (MR-WN), MR-WN with subsoiling to ~40 cm depth after maize harvest (MS-WN) and no straw return (MN-WN). Results showed that the MS-WR had the greatest grain yields of both wheat and maize, gross revenue and economic profit with increases of 45.5%, 35.6%, 26.5%, and 79.7% relative to the MN-WN, respectively. Compared with the initial SOC level, the SOC stock increased by 22.9% under MS-WR, following by MR-WR (16.0%), MS-WN (11.6%), MR-WN (8.0%), MN-WR (5.1%), and MN-WN (−3.8%). The MS-WR reduced the net CF and net CF per economic profit by 35.4% and 64.1% relative to the MN-WN although it elevated the CF by 25.3%. Therefore, adopting the integrated strategies of both maize and wheat straw return with subsoiling to ~40 cm depth after maize harvest represented an economically and C-friendly optimal field management practice for intensive wheat-maize double cropping production in the Guanzhong Plain or other regions with similar environmental conditions in the world.

Optimizing Nitrogen Recommendations for Tillage and Corn Residue Management in Irrigated Wheat, Southern Iran

ABSTRACT In southern Iran, intensive tillage operations and residue removal have been the major cause of declining crop productivity and nitrogen-use efficiency (NUE). A 2-year field experiment (2016–2017) was conducted to test four nitrogen (N) rates (0, 101, 152, and 202 kg N ha−1) and tillage practices (conventional, CT; reduced, RT; and no tillage, NT) effects on irrigated wheat (Triticum aestivum L.) grown with or without corn (Zea mays L.) residue removal, using a split-plot design with three replications near Shiraz, Iran. After 2 years, wheat yields were tended to be increased with increasing N rates from 101 to 202 kg N ha−1 under RT with residue retention. Increasing N rate decreased NUE values particularly N physiological efficiency (PEN). Likewise, the lowest NUE was obtained under NT, while RT and CT either showed similar effects or RT was superior over CT. Furthermore, the NNI value around 1 was obtained at 152 kg N ha−1 under RT, when crop residues were retained or removed. Our research has shown that replacing CT with conservation tillage (especially RT) with residue retention and 152 kg N ha−1 can greatly protect wheat yield and optimize NUE values under wheat- and corn in a rotation, but it is based on the short-term results and evaluation of long-term experiment is highly recommended.

Cover Crop Management on the Southern High Plains: Impacts on Crop Productivity and Soil Water Depletion.

Simple SummaryAgriculture throughout the Southern High Plains of the United States relies on supplemental irrigation from the Ogallala Aquifer because of limited precipitation and high evapotranspiration rates. Unfortunately, extraction rates greatly exceed the recharge rate of the aquifer. This region is prone to soil erosion, so maintaining soil coverage is critical for protecting soil resources. Despite the many benefits of planting cover crops, producers do not readily plant winter crops in the Southern High Plains due to concerns of depleting soil water availability for subsequent summer crops. Based on the results of this experiment, producers can plant rye with a no-till drill to help maintain soil cover and produce high-quality winter forage for grazing livestock without threatening soil water supply for the summer crops; in this case, teff. Light irrigation (up to 25 mm per month) should be applied to supplement rainfall and ensure grazing if the producer is reliant upon the rye and does not have other forage available for contingency. Finally, timely termination of the cover crops is critical. Delayed termination of the cover crops was the biggest factor found to reduce the productivity of the teff.The imminent depletion of the Ogallala Aquifer demands innovative cropping alternatives. Even though the benefits of cover crops are well recognized, adoption has been slow in the Southern High Plains (SHP) of the United States because of concerns that cover crops withdraw soil water to the detriment of the summer crops. This small plot experiment tested the interacting effects—production, soil water depletion of the cover crops, and subsequent teff [Eragrostis tef (Zucc.) Trotter] summer hay crops—of irrigation and tillage management with five cover crop types to identify low-risk cover crop practices in the drought-prone SHP. Dryland rye (Secale cereale L.) produced modest forage biomass (>1000 kg ha−1), even in a dry year, but it was found that light irrigation should be used to ensure adequate forage supply (>1200 kg ha−1) if winter grazing is desired. No-till management and timely termination of the winter cover crops were crucial to reducing the negative impact of winter crops on summer teff production. The results indicated no detriment to soil water content that was attributable to planting no-till cover crops compared with the conventional practice of winter fallow. Therefore, producers could take advantage of the soil-conserving attributes of high-quality winter forage cover crops without experiencing significant soil water depletion.

Tillage, green manure and residue management accelerate soil carbon pools and hydrolytic enzymatic activities for conservation agriculture based rice-wheat systems

ABSTRACT We studied the effects of tillage, crop residues, and green manure on soil carbon pools and hydrolytic enzyme activity in a sandy loam after five cycles of the rice-wheat system (RWS). Four main plot treatments in rice were combinations of wheat straw and Sesbania green manure (GM) management: (1) puddled transplanted rice (PTR) with no wheat straw, (2) PTR with 25% wheat stubbles (12–15 cm long) retained, (3) PTR with no wheat straw plus GM, and (4) PTR with 25% wheat stubbles plus GM. Three subplots treatments in subsequent wheat were (1) conventional tillage with rice straw removed, (2) zero tillage (ZT) with rice straw removed, and (3) ZT with 100% rice straw retained as a surface mulch. The results showed that PTR with wheat stubbles retained plus GM and ZT wheat with rice straw retained (ZTWRS100) significantly (p< 0.05) increased all the carbon pools and hydrolytic enzymes except phenol oxidase and peroxidase activities. The carbon management index under ZTWRS100 retained was significantly higher than zero-till or conventional till wheat without residue. The principal component analysis identified active carbon, less labile carbon pools; xylanase and dehydrogenase hydrolytic enzymes as the most reliable sensitive indicators for assessing soil quality for conservation agriculture (CA) – based practices in RWS. The study showed that adoption of PTR with 25%-anchored wheat stubbles retained plus GM in rice followed by ZTWRS100 in wheat was the best crop production strategy for enhanced carbon pools, hydrolytic enzymatic activities and gives an idea of its overall fitness for carrying out ecosystem functions.

PHYSICO-CHEMICAL PROPERTIES OF AN ALFISOL UNDER DIFFERENT TILLAGE SYSTEMS IN THE BASEMENT COMPLEX OF KOGI STATE

It is necessary to evaluate the physico-chemical properties of soils under continuous tillage in other to be able to manage the soil sustainably. This study evaluates the physico-chemical properties of soils under fallow, manual tillage and conventional tillage systems for the past fifteen years. Soil samples were collected in 0-20cm depth and analyzed for particle size distribution, soil organic matter, soil nitrogen, soil phosphorus, soil pH, organic carbon, water holding capacity, cation exchangeable capacity (CEC), porosity, moisture content (MC) and bulk density (BD). Results shows that the soil of the area is sandy, the fallow and mechanized farming area are strongly acidic while the manually tilled land is moderately acidic. Furthermore, the fallow had the highest values of organic matter, available phosphorus, total nitrogen, exchangeable sodium and potassium, CEC, moisture content and porosity (2.35%, 7.57ppm, 0.385%, 8.69%, 27.79%, 7.7%, 3.00%, 48.00% and 54.00% respectively) while the lowest values were obtained in the mechanized tilled land area. This established evidence of depletion of soil properties due to long term mechanized tillage in the study area, therefore sustainable practices targeted at restoring and sustaining the soil productivity are suggested.

Durum Wheat (Triticum turgidum ssp. durum) and its Comparison to Bread Wheat in Some Aspects

Durum wheat is an important cereal produced mainly in Middle East, North Africa, South Europe and North America. Under Mediterranean conditions, water deficiency and high temperature during reproduction period limit durum crop production severely. Water deficit is the major limiting factor in Mediterranean basin and durum yield is greatly reduced by drought in this zone. Origin, grain quality, diseases tolerance, adaptation to environmental conditions and changes and consumption areas of this species are different than common wheat. Old durum landraces are now replaced with modern cultivars due to demand of higher technological quality requirements from food industry. Wild emmer wheat gene pool is a major source for durum wheat genetic and breeding improvements. Breeders increased productivity and resilience of durum wheat by strong selection of genes managing important agronomical traits. Cropping system, tillage management and weather conditions can greatly affect durum wheat and common wheat grain yield and quality. Here in this review, knowledge extracted and selected from latest articles published in high quality articles in the last decade on durum wheat are mentioned and some of them are compared to bread wheat. Different than a systematic presentation of well known informations related to wheat and durum, as it will require hundred of pages, here in this mini review, it was targeted to present some interesting aspects of relation of durum wheat to common wheat.

Utjecaj obrade tla i malča na strukturu tla, zbijenost i prinos soje u Hrvatskoj

Soil tillage management can have positive and negative short-term effect on agroecosystem. Therefore, searching for optimal tillage management is crucial for the maintenance and improvement of soil functions. The purpose of this study was to analyze the impact of conventional tillage (CT), minimum tillage (MT) and reduced tillage (RT) on Fluvisols in humid environments (Croatia). Under each treatment, subplots with and without straw were applied. The impact was assessed on physical soil properties and soybean (Glycine max (L.) Merr.) yield. Soil bulk density was significantly lower in RT with straw when compared to the other treatments. Straw significantly effected bulk density at 10-20 cm depth. Penetration resistance did not exceed the value of 2.5 MPa on any treatment, it was also significantly reduced on covered plots in Autumn. Soil water content showed higher values in straw treatments at MT and RT. Water stable aggregates percentage were high at straw plots and at MT and RT in addition to CT. Moreover, soybean grain yield was higher in straw plots at RT and MT. It can be recognized in the aspect of short-term results that the MT and RT is an advisable alternative for CT due to its positive impact on soil physical condition and grain yield.