•No-tillage have greater Organic Matter (OM) than conventional tillage over time.•OM content improve soil quality after 10-yr.•14-yr are required to no-tillage surpass rice yield of conventional ...tillage.
No-tillage (NT) systems have arisen as a promising alternative to traditional rice cultivation in flooded soils, such as pre-germinated (PG) and conventional tillage (CT) systems. However, how NT affects soil properties and grain yield is not completely understood, especially over the long term. The objective of this study was to evaluate the long-term impact of three tillage systems (CT, NT and PG) on soil chemical, physical and biological attributes and the influence of these attributes on rice yield over time in a lowland soil of the Brazilian subtropical region. The rice grain yield was evaluated for 16 growing seasons, and the soil properties were evaluated from 17 to 21 years after the beginning of the experiment. After 14 growing seasons, rice yield was greater (3.4%) under the NT system compared to under the CT system. The increase in rice yield over time resulted in 67% greater soil organic matter (OM) content, exchangeable Ca and Mg and consequently cation exchange capacity (CEC) under the NT system compared to the CT and PG systems. In addition, soil bulk density and microbial C and N were 15%, 40% and 75% greater, respectively, under the NT system than under the CT system in the surface soil layer. The lack of soil disturbance associated with the high input of crop residues and flooding soil conditions favored the chemical, physical and biological soil properties through soil OM content, improving rice yields after 14 yr of NT adoption in relation to CT adoption.
•Potentially mineralizable N (N0) and labile C and N organic fractions were significantly correlated.•Labile N fractions were higher in NT than in CT at all three depths.•The N0 proved to be ...positively influenced by the quantity and quality of POM-C.•Crop N uptake was not related to N0 for any tillage system and depth.
Tillage systems strongly affect nitrogen (N) mineralization. However, there is still only limited information on the relationship between N in labile soil organic matter (SOM) fractions and crop N uptake under different tillage systems in areas with poor water availability. This study discusses the long-term effect of two tillage systems on i) the N-content in labile organic matter fractions and their relationship with the N mineralization potential at three depths (0–5; 0–10 and 0–20cm), ii) the factors that affect the N mineralization potential, and iii) the relationship between potentially mineralizable N (N0) and crop N uptake in a semi-humid climate. In a long-term experiment, a Typic Argiudoll was sampled under two contrasting tillage systems: no-tillage (NT) and conventional tillage (CT). The soil sampling was performed over four years of the crop sequence (2003, 2009, 2010 and 2011) when the plots were sown with winter wheat (Triticum aestivum L.). They were analyzed for N0 in the form of anaerobic N, soil organic nitrogen (SON), physically separated SOM fractions and crop N uptake. Higher values of SON and labile soil N fractions were observed under NT at all three depths. Significant differences in N0 were found between the tillage systems, with greater values under NT. Significant (P<0.05) and positive correlations between N0 and fine particulate organic carbon (fPOM-C) (r≥0.66) were found in CT and in NT at the three depths, whereas highly significant (P<0.001) and negative relationships between N0 and fine particulate organic N (fPOM-N) (r≥−0.83) were found under both tillage systems at 0–5 and 0–10cm. The most pronounced difference in these relationships between tillage systems was observed at the 0–5cm soil depth. Significant correlations of N0 with residue input from previous crops and the fallow period were observed under both tillage systems and for all three depths. Regarding the relationships between N0 and wheat N uptake, no significant correlations were found for any tillage system or depth. Soil organic N fractions were shown to be strongly influenced by the residue input from the previous crop and by variable weather conditions during the fallow period. The higher content of SON fractions under NT was associated with a higher N mineralization potential, however, it did not result in increased N availability and N uptake by wheat, because of climatic conditions during the crop growing season.
•Weed richness and evenness did not differ among non-inversion and no tillage systems.•Inter-annual variability appears as the main factor determining weed communities.•Crop type modulated weed ...community composition and diversity.
Both no-tillage and non-inversion tillage systems have been proposed within the context of 'conservation agriculture' as alternatives to conventional tillage for weed management and soil conservation. However, little information is available regarding their influence on weed community diversity and crop yield in Mediterranean cereal steppelands. Type of tillage represents a crop abiotic factor that largely influences the environmental conditions at the field scale to which weed communities may respond. The present paper examines the effect of no-tillage, subsoil tillage and minimum tillage (the latter two being non-inversion systems), on arable weed community diversity and composition in a cereal-legume crop rotation over 9 years. Their effects on crop yield are also explored. Inter-annual environmental variability was found to be more important than the tillage system in determining weed species diversity and assembly. None of the studied tillage systems exerted consistent effects, neither on weed community diversity nor on crop yields. In addition, the effect of tillage system on weed community diversity was crop-type dependent. The main effects of tillage systems were related to the composition of weed communities. Less common species resulted particularly affected while core species were consistent across tillage systems.
•No-till and high C input are key to avoid soil degradation in newly irrigated areas.•Lower stability of aggregates led to soil crusting under conventional tillage.•Long-term no-till led to greater ...soil organic carbon content.•Long-term no-till enhanced aggregate stability and early corn development.•No-till avoids soil crust formation, securing corn yield, in newly irrigated areas.
The aim of this study was to determine the most appropriate soil management to reduce the structural degradation of soils susceptible to crusting in Mediterranean areas recently transformed into irrigation. A long-term field experiment (LTE) under rainfed conditions was established in 1996 in NE Spain to compare three tillage systems (no-tillage, NT; reduced tillage, RT; conventional tillage, CT). The experiment was transformed to irrigated corn in 2015. In 2015, an adjacent experiment with the same layout was created (short-term experiment, STE) in an area previously managed under long-term NT. The study was carried out during the second corn growing season (i.e. year 2016). Soil samples were collected from 0 to 5cm depth at different dates during corn season. Dry and water-stable macroaggregates and their C concentration, soil organic carbon (SOC) and labile C concentration, soil respiration, bulk density, penetration resistance (PR), water infiltration, macroporosity, microporosity, amount of crop residues and ground cover, corn development, aerial biomass, and grain yield were measured. In LTE and STE tillage led to a breakdown of dry sieved aggregates (of 2–4 and 4–8mm size) in RT and CT, being slowly reconsolidated throughout the corn growing season. However, macroaggregate water-stability did not increase in CT and RT compared to NT due to a lower SOC concentration, making the soil more susceptible to its degradation by the action of water. SOC differences between treatments were more pronounced in LTE than STE given the long-term differential management in the first, which allowed greater accumulation of SOC under NT. In LTE, PR between corn rows was greater under NT than CT and RT and non-significantly different between treatments within the row. In the case of STE, PR increased over time after tillage (CT and RT) to match NT in the last sampling. Crop establishment was slower in CT than NT in LTE highlighting the impact of soil surface degradation on crop development. However, contrarily to the differences in corn yield in 2015, a careful planting in 2016 led to a lack of differences between tillage systems on corn yield. Our results indicate that in areas transformed into irrigation intensive tillage leads to greater susceptibility to soil structural degradation. Thus, in these areas the adoption of conservation agriculture practices such RT and NT enhances soil resilience to degradation processes and ensures an adequate development of the crop.
•Macroaggregation was greater under NT compared to CT.•NT promotes occluded-C accumulation mainly in macroaggregates.•The increase in occluded-C accumulation leads to organomineral ...association.•Legume cover cropping favors the mineral-associated C enrichment in microaggregates.
Both no-tillage and legume cover crops have been shown to increase soil organic carbon (SOC) in subtropical soils. However, the mechanisms underpinning management system effects on SOC accumulation are still not well understood. We used a combination of aggregate size and density fractionation to elucidate these mechanisms at a 30-year old experiment on an Acrisol in southern Brazil. The effects of two tillage systems conventional system (CT) and no-tillage (NT) combined with three cropping systems oat/maize (O/M), vetch/maize (V/M) and oat + vetch/maize + cowpea (OV/MC) were evaluated in the top 20 cm soil layer. Overall, macroaggregation (>0.25 mm) was significantly influenced by tillage with NT showing values 14% greater than CT in the 0–5 cm soil depth. On average, the occluded light fraction-C content in macroaggregates was more than twice as high under NT compared to CT (4.4 vs. 1.8 g kg−1). This effect was more pronounced when legume cover crops were grown. However, the most significant effect of cover crops was observed in the organomineral fraction of microaggregates, especially under NT (12.1 under O/M and 19.8 g kg−1 under OV/MC). Our results suggest that, although NT increased the occluded light fraction-C compared to CT, this effect was smaller than the gains that legume cover crops offered in organomineral association.
No-tillage (NT) is an alternative technique adopted in cassava (Manihot esculenta Crantz) growing areas to reduce soil loss. However, it may affect the development of storage roots depending on the ...soil-covering residues. This study evaluated the soil and water losses and storage root yield and quality of cassava planted in the dry and rainy seasons using conventional tillage (CT) and NT, following sole maize (Zea mays L.) cropping or maize–palisadegrass Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster intercropping. The experimental design was a randomized block with five replications. Four treatments were considered representing cassava planted using CT and NT following sole maize or maize–palisadegrass intercropping. CT caused soil loss of up to 43.4 Mg ha−1 over the 16 months of cassava cultivation. NT following maize–palisadegrass intercropping did not decrease cassava yield nor its quality and reduced both soil and water losses. In the rainy planting season, NT reduced soil loss by up to 80% (35 Mg ha−1), while in the dry planting season, the reduction varied between 28% and 38% (8–11 Mg ha−1). These findings suggest that previous maize–palisadegrass intercropping followed by NT of cassava is recommended for increasing soil conservation, especially in cassava planted in the rainy season.
•For cassava planted with conventional tillage (CT), soil loss reaches 43.4 Mg ha−1.•In the rainy season, soil loss in the CT is 1.46-fold greater than in the dry season.•No-tillage reduces soil losses by 80% in cassava planted in the rainy season.•Cassava root, starch, and flour yield is not affected by no-tillage.
•No-tillage significantly increased soil CO2 emissions at the highest N-fertilizer rate.•Soil CO2 emission depends on soil temperature and moisture.•Soil acted as a CH4 sink in all ...treatments.•Reduced and no-tillage increased above-ground C-inputs at the highest N-fertilizer rate.
In newly irrigated Mediterranean agroecosystems, the combined effect of tillage and N fertilization on soil carbon dioxide (CO2) and methane (CH4) fluxes is at present poorly understood. The goal of this study was to quantify both soil CO2 and CH4 emissions as well as crop performance under different tillage systems and N fertilization rates during three maize (Zea mays L.) growing seasons (2015–2017) in a semiarid area converted to irrigated. Three types of tillage (conventional tillage, CT, reduced tillage, RT, and no-tillage, NT) and three mineral N fertilization rates (0, 200, and 400 kg N ha−1) were compared in a randomized block design with three replications. Weekly soil CO2 and CH4 emissions, soil temperature and gravimetric moisture were measured. Moreover, maize above-ground biomass, grain yield, and above-ground C-inputs were quantified. Carbon dioxide emissions ranged from 173 to 4378 mg CO2-C m-2 d-1. No-tillage showed a greater mean soil CO2 flux than CT when applying the highest rate of N (400 kg N ha-1). Although some emissions of CH4 were observed, all treatments acted as net CH4 sinks during most of the experimental period. A linear multiple relationship between soil CO2 fluxes and soil gravimetric moisture (0–5 cm depth) and temperature (10 cm depth) were found. In the 2015 growing season, greater cumulative CO2 emissions were found under NT and RT compared with CT, while in 2016 N T showed the highest values compared to CT with intermediate values in RT. Differently, in 2017 no differences between tillage systems were found. When applying N fertilizer, NT and RT increased maize grain production and above-ground C-inputs compared to CT, since a severe soil crusting occurred in this last, which caused crop water deficit. The results suggest that tillage intensity and N fertilization rate reduction can increase maize biomass production and yield which leads to greater C-input that returns to the soil.
The adoption of less intensive soil cultivation practices is expected to increase earthworm populations and their contributions to ecosystem functioning. However, conflicting results have been ...reported on the effects of tillage intensity on earthworm populations, attributed in narrative reviews to site‐dependent differences in soil properties, climatic conditions and agronomic operations (e.g. fertilization, residue management and chemical crop protection). We present a quantitative review based on a global meta‐analysis, using paired observations from 165 publications performed over 65 years (1950–2016) across 40 countries on five continents, to elucidate this long‐standing unresolved issue. Results showed that disturbing the soil less (e.g. no‐tillage and conservation agriculture CA) significantly increased earthworm abundance (mean increase of 137% and 127%, respectively) and biomass (196% and 101%, respectively) compared to when the soil is inverted by conventional ploughing. Earthworm population responses were more pronounced when the soil had been under reduced tillage (RT) for a long time (>10 years), in warm temperate zones with fine‐textured soils, and in soils with higher clay contents (>35%) and low pH (<5.5). Furthermore, retaining organic harvest residues amplified this positive response to RT, whereas the use of the herbicide glyphosate did not significantly affect earthworm population responses to RT. Additional meta‐analyses confirmed that epigeic and, more importantly, the bigger‐sized anecic earthworms were the most sensitive ecological groups to conventional tillage. In particular, the deep burrower Lumbricus terrestris exhibited the strongest positive response to RT, increasing in abundance by 124% more than the overall mean of all 13 species analysed individually. The restoration of these two important ecological groups of earthworms and their burrowing, feeding and casting activities under various forms of RT will ensure the provision of ecosystem functions such as soil structure maintenance and nutrient cycling by “nature's plough.”
For the first time, we provide quantitative evidence showing that no‐tillage and conservation agriculture significantly increase earthworm abundance and biomass. We also identified several explanatory variables (climatic and edaphic properties, agronomic practices including organic matter and herbicide applications) that modulated these responses. Additional meta‐analyses confirmed that reduced tillage resulted in population increases in epigeic and anecic earthworms which will be critical to ensure soil ecosystem functions.
Conservation agriculture (CA) is advocated as a sustainable farming method to improve soil health, increase crop yields and food security, while reducing input costs. In South Africa, a country with ...low rainfall, limited agricultural lands and a large smallholder farming community, implementing CA is imperative. To investigate the research status of CA in South Africa, a systematic review of available literature was conducted. Conservation agriculture initiatives as captured in the form of peer-reviewed publications, reports, dissertations, proceedings and projects were collected. Relevant data, such as location, type of research, CA treatments implemented, duration of interventions, main results, limitations and challenges were recorded. Most literature were in the form of peer-reviewed publications (45%). The CA interventions mostly occurred as researcher-managed field trials (60%), followed by farmer-led trials. While the interventions were fairly scattered throughout the country, there was a poor correlation between major crop-producing areas and research focus. Conservation agriculture interventions generally had a positive effect on soil properties and crop yield. Important limitations include poor reporting, short trial periods and insufficient data collection. Local research involving farmers is needed to support best-management practices for different agro-ecological zones.
PDF
