Effects Of Conservation Tillage Practices Research Articles

Conservation Tillage Practices and Their Role in Sustainable Farming Systems

Conservation tillage practices have become increasingly recognized as crucial strategies in the effort to achieve sustainable farming systems. These practices, which include methods such as notill, striptill, mulchtill, and ridgetill, aim to minimize soil disturbance, thereby promoting a range of environmental, economic, and agronomic benefits. This review article delves into the different types of conservation tillage practices, elaborating on their specific techniques, advantages, and potential drawbacks. It examines how these practices influence soil health by enhancing soil structure, increasing organic matter, and fostering biodiversity. Furthermore, the article discusses the impact of conservation tillage on crop productivity, highlighting both the yield benefits and the challenges related to pest and weed management. The role of conservation tillage in mitigating environmental issues such as soil erosion, water conservation, and greenhouse gas emissions is also explored in depth. Through a synthesis of recent research findings and case studies, this article provides a thorough analysis of the contributions of conservation tillage to sustainable agriculture. It also offers practical recommendations for farmers, policymakers, and researchers to optimize the adoption and effectiveness of conservation tillage practices, ultimately aiming to support a transition towards more resilient and sustainable farming systems.

Potential of conservation tillage, cover crops, and digestate application as integrated C farming practices for processing tomato

Conventional soil management — based on intensive tillage and low input of organic material – negatively impacts soil quality via carbon (C) losses as carbon dioxide emissions (CO2), exacerbating the effect of climate change on agriculture. Carbon farming practices (CFPs), such as minimum tillage (MT) and strip tillage (ST), offer promising solutions to maintain soil fertility, sustain crop yields, and mitigate environmental impacts. However, applying CFPs in processing tomato (Solanum lycopersicum L.) cropping presents unique challenges due to specific crop and tillage characteristics. Our two-year field study investigated the effects of conservation tillage practices (i.e., MT and ST), both combined with cover crops and digestate application, on soil quality parameters and processing tomato yield. The field studies were conducted in fields with varying soil textures (i.e., clay and silty clay loam), and aimed to evaluate responses in terms of soil C sequestration, nutrient concentrations, soil structure, and abundance of earthworms. We hypothesized that both MT and ST would enhance soil quality parameters also in tomato cropping systems, with ST potentially outperforming MT in C sequestration. Results revealed that CFPs significantly increased soil organic matter, total nitrogen, and available phosphorous compared with conventional tillage. Both MT and ST increased soil C sequestration (up to 1.06 Mg C ha−1 y−1 and 1.21 Mg C ha−1 y−1, respectively) compared with conventional tillage (CT), which lost around 0.88 Mg C ha−1 y−1 under silty-clay loam soil, and had negligible C sequestration (+0.02 Mg C ha−1 y−1) under clay soil. We found no significant difference between MT and ST when using the equivalent soil mass method for calculating C sequestration. Noteworthy, CFPs enhanced fertility parameters without a negative impact on yields, underscoring their potential for enhancing soil C sequestration, improving nutrient availability, and supporting processing tomato yield under adaptation scenarios to climate change.

The impact of conservation tillage intensities on mean yields and yield risk

Understanding the productivity and production risk effects of conservation tillage practices are important so that growers can make better decisions about tillage systems appropriate for their farm operations. This study investigates the mean yield and yield risk effects of conservation tillage practices with varying levels of tillage intensity and timing. Long-term field trial data for corn (Zea mays, L.) and soybeans (Glycine max, L. Merr.) in the North Carolina Piedmont, together with moment-based regression models, were used to achieve the objective of the study. Our empirical analysis suggests that conservation tillage treatments (with lower tillage intensities and higher residue levels) consistently have higher mean yields than conventional tillage practices in the sandy loam soils of the North Carolina Piedmont. However, we find that conservation tillage practices with lower intensities (and higher residue levels) do not generally have a consistent statistically significant risk reducing effect based on the higher-order moments of the yield distribution (e.g., variance, skewness, and kurtosis). This indicates that conservation tillage does not consistently result in statistically lower production risk relative to conventional tillage methods.

Effect of Zero and Minimum Tillage on Cotton Productivity and Soil Characteristics under Different Nitrogen Application Rates

Long-term conservation tillage and straw incorporation are reported to improve the soil health, growth, and yield traits of crops; however, little is known regarding the optimal nitrogen (N) supply under conservation tillage with straw incorporation. The present study evaluated the effects of conservation tillage practices (ZTsas: zero tillage plus wheat straw on the soil surface as such, and MTsi: minimum tillage plus wheat straw incorporated) and different N application rates (50, 100, 150, and 200 kg ha−1) on the yield and quality traits of cotton and soil characteristics in a five-year field experiment. The results showed that ZTsas produced a higher number of bolls per plant, boll weight, seed cotton yield, 100-seed weight, ginning out-turn (GOT), fiber length, and strength than MTsi. Among different N application rates, the maximum number of bolls per plant, boll weight, seed cotton yield, GOT, 100-seed weight, fiber length, strength, and micronaire were recorded at 150 kg N ha−1. Averaged over the years, tillage × N revealed that ZTsas had a higher boll number plant−1, boll weight, 100-seed weight, GOT, fiber length, and strength with N application at 150 kg ha−1, as compared to other tillage systems. Based on the statistical results, there is no significant difference in total soil N and soil organic matter among different N rates. Further, compared to MTsi, ZTsas recorded higher soil organic matter (SOM, 8%), total soil N (TSN, 29%), water-stable aggregates (WSA, 8%), and mean weight diameter (MWD, 28.5%), particularly when the N application of 150 kg ha−1. The fiber fineness showed that ZTsas had no adverse impact on fiber fineness compared with MTsi. These results indicate that ZTsas with 150 kg N ha−1 may be the optimum and most sustainable approach to improve cotton yield and soil quality in the wheat–cotton system.

Near-saturated soil hydraulic conductivity and pore characteristics as influenced by conventional and conservation tillage practices in North-West Himalayan region, India

Tillage plays an important role in modifying soil hydraulic properties. The objective of the present study was to evaluate the effect of conservation tillage practices in a maize-wheat cropping system on near-saturated soil hydraulic properties and pore characteristics in the North-West Himalayan region, India. Three treatments viz. conventional tillage (CT), minimum tillage (MT), and zero tillage (ZT) were evaluated in terms of field saturated hydraulic conductivity (ks), unsaturated hydraulic conductivity k(h), the inverse of capillary length (α), flow-weighted mean pore radius (r0), numbers of pores per square meter (n0) and water-conducting macroporosity (Ɛ). The above hydraulic conductivity and pore characteristics were derived from steady-state water flux (q) measured using hood infiltrometer at 0, −1, and −3 cm pressure head for each treatment after seven years of establishment of this tillage experiment. Results revealed significantly (p < 0.05) higher values of ks, k(h), α, and Ɛ in ZT as compared with CT. MT had intermediate values. Higher α values suggested a greater gravity-dominated flow under ZT and MT as compared with CT. Analysis of r0 values indicated better connectivity of pores in ZT and MT as compared with CT. Macropore flow suggested that on average pore radii, > 0.50 mm conducted about 63.60, 68.01, and 75.97 % of total flow (at 0 cm pressure head) in the corresponding water-conducting macroporosity of 0.00030, 0.00044, and 0.00069 % of soil volume under CT, MT, and ZT, respectively. Overall, zero-tillage based agriculture system was found to improve near-saturated soil hydraulic properties.

Effect Of conservation tillage practices on aroma, yield and quality of mechanical-transplanting fragrant rice

ABSTRACT In our study, two popular fragrant rice cultivars (Meixiangzhan 2 and Xiangyaxiangzhan) were conducted by three treatments (CK: conventional tillage; T1: minimum tillage; T2: no-tillage) to assess the effects of conservation tillage on the aroma, yield and quality of mechanical-transplanting fragrant rice. Results depicted that the 2-acetyl-1-pyrroline (2-AP) content in mature grains of mechanical-transplanting fragrant rice remained high level under T1 and T2 treatments. 2-AP accumulation in mature grains was significant associated with the 2-AP, proline and pyrroline-5-carboxylic acid content, proline dehydrogenase and ornithine aminotransferase activity in grains and leaves during the grain-filling period. T1 and T2 treatments improved yield components, increased the photosynthetic matter accumulation, and increased yields. T1 and T2 treatments also resulted in a higher head milled rice rate and significant changes in protein content of mechanical-transplanting fragrant rice. Overall, conservation tillage practices were beneficial to increase the 2-AP content, quality and yield of mechanical-transplanting fragrant rice.

Effect of conservation tillage practices on growth attributes of different fodder crops and soil moisture depletion

A field experiment was conducted at Central Research Farm, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India during summer season of 2016 and 2017to find out effects of various tillage practices on growth and yield of different fodder crops and soil moisture depletion. The experiment was framed in split plot design comprising 3 tillage practices (zero, minimum and conventional tillage) in main plot and 4 fodder crops (maize, sorghum, rice bean and cowpea) in sub plot, replicated thrice. Pooled data revealed that zero tillage significantly performed well in ensuring best growth of all the fodder crops over others. However, crops showed variable response among each other regarding growth attributes due to its differential genetic makeup and morphological features. Accordingly, green forage yield also varied. Soil moisture depletion was also found to be low when rice bean was grown under zero tillage practice. Overall, the study confirms the efficacy of conservation tillage (zero tillage and/or minimum tillage) on growth of these fodder crops and soil moisture conservation in this region and agro-climatic condition over conventional tillage.

Microbial-derived carbon components are critical for enhancing soil organic carbon in no-tillage croplands: A global perspective

Soil organic carbon (SOC) is an important component of the global carbon (C) cycle, while tillage has been shown to significantly impact SOC stocks, its impact on the different SOC fractions is not well understood at global level, making it difficult to predict the behavior of SOC over time. Using data from 95 studies on a global level, we investigated the changes of various SOC fractions in 0-400 mm [dissolved organic C (DOC), particulate organic C (POC), easily oxidizable organic C (EOC), microbial biomass C (MBC), and mineral-associated organic C (MOC)] with NT application. This study also quantified the roles of different environmental and agronomic factors (e.g., climatic conditions, soil texture and nutrient conditions, study duration, and cropping intensity) in the changes of these SOC fractions. Compared to conventional tillage (CT), NT and reduced tillage (RT; tillage systems that are less intensive, with fewer trips in the field than CT) increased SOC concentrations, which were 7.4% higher in NT than in RT (percentage change based on weighted response ratio). Compared with CT, NT significantly increased DOC (17.6%), POC (11.7%), EOC (14.8%), MBC (33.1%), and MOC concentration (16.0%). Furthermore, POC, MBC, and MOC concentrations were 8.2, 34.1, and 4.4% higher in NT than in RT, respectively. Importantly, the increased SOC concentrations under NT were significantly correlated with MBC (R2 = 0.62) and POC (R2 = 0.55). Soil depth and mean annual temperature were the dominant factors affecting the response ratios of SOC fractions (DOC, EOC, MBC, MOC, and POC) under NT, followed by the duration of NT application. Our results suggest that SOC fractions, especially those driving soil biological activities (rather than total SOC), should be considered when evaluating the effects of conservation tillage practices on SOC sequestration. We highlight the development of site-specific strategies to effectively manage C stocks and to enhance local parameterization while developing biogeochemical and Earth system models.

Effect of conservation tillage practices on rice fallow sunflower (Helianthus annuus L.) at Odisha

Sunflower is an emerging profitable rice fallow crop at Odisha. An experiment at College of Agriculture(OUAT) Bhubaneswar on rice fallow sunflower conducted to standardize tillage, fertilizer dose and suitable hybridhas shown that sunflower hybrid KBSH 44 performed better than other hybrids under zero tillage at 150% RDF andregistered the maximum nutrient uptake.

Minimum tillage and residue retention increase soil microbial population size and diversity: Implications for conservation tillage.

A global meta-analysis was conducted to evaluate the effect of conservation tillage practices on soil microbial population size [based on microbial count and phospholipid fatty acid (PLFA) measurements], diversity (Shannon index), and microbial community structure. Both no-tillage (NT) and NT plus residue retention (NTS) increased soil microbial count as compared with conventional tillage (CT). Bacteria, fungi, and actinomycete counts were 3%, 18%, and 28%, respectively, higher under the NTS treatment relative to the NT treatment, and 38%, 41%, and 28%, respectively, higher in the CT plus residue retention (CTS) treatment than in the CT treatment. No-tillage, as compared to CT, increased total PLFAs by 11%. The concentration of fungal PLFAs was increased by 17% by NT as compared to CT, but was decreased by 52% by NTS as compared to NT. The actinomycete PLFA concentration was decreased by reduced tillage and CTS, compared to CT. Compared with CT, NT increased the Shannon index of the total microbial and bacterial communities by 4% and 6%, respectively. The bacterial count was negatively associated with mean annual precipitation (275-1624mm) and experimental duration (1-35years) and positively associated with initial total soil nitrogen concentration. Overall, relative to CT, minimum tillage alone increased soil microbial count, fungal biomass, and bacterial diversity; residue retention alone increased soil microbial count and fungal diversity, and decreased the biomass of actinomycetes; combining minimum tillage and residue retention increased soil microbial count and fungal diversity. We conclude that the response to minimum tillage and residue retention was consistently positive for soil microbial count but was context dependent for microbial biomass, diversity, and community structure.

Conservation tillage increases yield and precipitation use efficiency of wheat on the semi-arid Loess Plateau of China

Drought is a major limiting factor for rainfed spring wheat production on the semiarid Loess Plateau of China. Suitable tillage practices are important for improving precipitation use efficiency (PUE), which is the ratio of grain yield to annual precipitation. To obtain a better understanding of the effects of conservation tillage practices on PUE on the semiarid Loess Plateau, PUE was divided into five steps: precipitation storage efficiency, farmland water consumption rate, ratio of transpiration to evapotranspiration, crop transpiration efficiency, and harvest index. Six tillage practices were assessed in this paper, including conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw (NT), conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP), and no-till with plastic mulch (NTP), based on a long-term experiment initiated in 2001. The impact of tillage practices on soil quality, soil water storage, soil evaporation, biomass yield, and grain yield of spring wheat were monitored in 2015 and 2016. The results show that NTS improved soil quality and soil water storage before sowing. No-till with plastic mulch and NTS increased evapotranspiration but decreased evaporation, thus optimizing precipitation storage efficiency, the farmland water consumption rate, the ratio of transpiration to evapotranspiration, and crop transpiration efficiency, which gave rise to greater aboveground dry matter accumulation and more dry matter accumulation in grain. As a result, grain yield under NTS and NTP was significantly increased by 45 and 41 % compare to T, respectively, with corresponding improvements in PUE of 43 and 39 %. Therefore, both NTS and NTP have potential to substantially increase grain yield of spring wheat and PUE. However, for sustainable intensification in the long-run, NTS is the best combination of tillage and soil surface management for spring wheat production on the semi-arid Loess Plateau of China.

Residue retention and minimum tillage improve physical environment of the soil in croplands: A global meta-analysis

Conservation tillage practices, here defined as no-tillage (NT) or reduced tillage (RT) with/without residue retention, have been widely used to alleviate the negative effects caused by intensive tillage practices. Implementing effective and sustainable agriculture requires a deeper understanding of the impacts of conservation tillage practices on soil physical properties. This study examined the effects of conservation tillage practices on soil physical properties, including soil bulk density, aggregate size and stability, hydraulic properties, and soil pH; based on data collected from 264 studies published worldwide since 1980. The results indicated that no-tillage (NT), NT with residue retention (NTS), and reduced tillage (RT) increased bulk density by 1.4, 2.6, and 2.1%, respectively, compared with conventional tillage (CT). Soil bulk density decreased by 2.9% in NTS compared with NT, and 3.9% in RT with residue retention (RTS) compared with RT. The effect size of bulk density significantly decreased with the increasing experimental duration under NT and NTS practices. Compared to CT, conservation tillage practices increased aggregate mean weight diameter (MWD), geometric mean weight diameter and water stable aggregate (WSA) regardless of the residue retention or minimum tillage systems. The largest effect size of MWD (51.9%) and WSA (54.9%) appeared under NTS as compared to the CT. The effect size of MWD and WSA increased under NT with the increasing experimental duration. NT increased saturated hydraulic conductivity by 24.6% compared to CT. All conservation tillage practices increased soil available water capacity (AWC) compared with CT and NTS with a 10.2% increase in AWC compared with NT. The effect size of AWC increased under RT and NT practices with the increasing experimental duration. Soil pH decreased by 1.7 and 1.0% under RTS compared with RT and CT, respectively; and NT led to a 2.8% reduction in soil pH compared with CT. The effect size of soil pH decreased under RT and NT treatments with the increasing experiment duration. Overall, conservation tillage practices positively affected many soil physical properties; and the extent of the effects varied with the duration of the experiment.

Soil organic carbon mineralization and priming effects in the topsoil and subsoil under no-tillage black soil.

Priming effect is one of the important mechanisms regulating soil organic matter decomposition. However, the variation of priming effects in different soil layers remains unclear. In this study, we conducted a 30-day incubation experiment using no-tillage black soil from northeastern China. 13C-glucose and dynamic CO2 trapping methods were employed to investigate soil organic carbon (SOC) mineralization rates and the priming effect of the added 13C-glucose in the upper soil layer (0-10 cm) and the lower soil layer (30-40 cm). Our results showed that the cumulative SOC-specific mineralization rate in the upper layer was similar to that in the lower layer soil without glucose addition. Glucose addition significantly altered the mineralization rates in both layers, resulting in a positive priming effect (36.7%) in the upper layer but a negative priming effect (-12.4%) in the lower layer. The cumulative priming effect during the 30-day incubation was 3.24 mg C·g-1 SOC for the upper layer soil and -1.24 mg C·g-1 SOC for the lower layer soil. There was still a net SOC increase, even with positive priming effects in the upper layer soil. This was due to considerable amount of added glucose-C remained un-mineralized in the soil which would compensate the carbon loss from priming effects. Overall, our results demonstrated that the magnitude and direction of priming effects might differ between soil layers. Our findings contribute to a better understanding of the effects of conservation tillage practices (no-tillage and straw incorporation) on soil organic matter dynamics in agroecosystems.

Employment of GIS techniques to assess the long-term impact of tillage on the soil organic carbon of agricultural fields under hyper-arid conditions.

A study on six 50 ha agricultural fields was conducted to investigate the effect of conservation tillage practices on the long-term (1990–2016) changes in the soil organic carbon (SOC) content of the topsoil layers (0–10 cm) of agricultural fields. The experimental fields were selected from the 49 fields of the Tawdeehiya Arable Farm (TAF), located 200 kilometers southeast of Riyadh, the capital city of the Kingdom of Saudi Arabia. Data sets from laboratory determined SOC and the corresponding Landsat images generated vegetation indices, namely, the Normalized Difference Vegetation Index (NDVI) and the Bare Soil Index (BSI), were utilized for the prediction of SOC using multivariate regression techniques. Long-term changes in the SOC content of the experimental fields, as a result of different tillage practices, were also studied. The developed SOC prediction models exhibited high accuracy indicated by R2 values ranging from 0.73 to 0.85, RMSE values of 0.34 to 0.85 g kg-1 and P-values of less than 0.0001. The cross-validation results (R2 of 0.61–0.70, RMSE value of 0.34–0.85 g kg-1 and P-values of less than 0.0001) confirmed the high accuracy of the developed SOC prediction models. Results also revealed that the change in the SOC content was clearly associated with soil tillage practices. On the average, 76% of the all agricultural fields in the experimental farm showed a decrease of up to 24 g kg-1 in their SOC content after 10 years (1990–2000) of continuous conventional tillage practices. On the other hand, an average increase of up to 37 g kg-1 in the SOC content was observed in 88% of the studied fields at the end of the study period (2016), where conservation tillage was a continous and consistent practice in the experimental farm.

Conservation tillage and organic farming reduce soil erosion

AbstractThe impact of different arable farming practices on soil erosion is only partly resolved, and the effect of conservation tillage practices in organic agriculture on sediment loss has rarely been tested in the field. This study investigated rainfall-induced interrill sediment loss in a long-term replicated arable farming system and tillage experiment (the FAST trial) with four different cropping systems: (1) organic farming with intensive tillage, (2) organic farming with reduced tillage, (3) conventional farming with intensive tillage, and (4) conventional farming with no tillage. Measurements were carried out under simulated heavy rainfall events with runoff plots in 2014 (fallow land after winter wheat) and 2017 (during maize growth). Organic farming decreased mean sediment delivery compared to conventional farming by 30% (0.54 t ha−1 h−1). This study demonstrated that reduced tillage in organic farming decreased sediment delivery (0.73 t ha−1 h−1) compared to intensively tilled organic plots (1.87 t ha−1 h−1) by 61%. Nevertheless, the combination of conventional farming and no tillage showed the lowest sediment delivery (0.24 t ha−1 h−1), whereas intensively tilled conventional plots revealed the highest delivery (3.46 t ha−1 h−1). Erosion rates were much higher in June during maize growth (2.92 t ha−1 h−1) compared to those of fallow land after winter wheat (0.23 t ha−1 h−1). Soil surface cover and soil organic matter were the best predictors for reduced sediment delivery, and living plant cover from weeds in reduced organic treatments appeared to protect soil surfaces better than plant residues in conventional, no-tillage plots. Soil erosion rates were significantly lower when soil cover was above 30%. In conclusion, this study demonstrates that both organic farming and conservation agriculture reduce soil losses and showed for the first time that reduced tillage practices are a major improvement in organic farming when it comes to soil erosion control.

Weed dynamics in conservation agricultural systems as influenced by conservation tillage and nutrient management practices under rainfed finger millet

Weeds are major threats for loss of yield in any cropping system. Especially in conservation tillage systems, it is a basic necessary requirement to keep the weed population below their threshold levels to realize optimum grain yields. Managing weeds in conservation tillage systems are very essential to optimize crop production. Hence, to study the effect of conservation tillage practices on weed dynamics, soil weed seed bank and their distribution, a field experiment was conducted under rainfed finger millet (Eleusine coracana (L.) Gaertn.) on Alfisols for two consecutive seasons during 2014 and 2015 at All India Coordinated Research Project on Dryland Agriculture, University of Agricultural Sciences, GKVK, Bengaluru, India under split-plot design with three main plots (different tillages) and five sub-plots (different nutrient management). Conventional tillage has recorded significantly higher grain and straw yield of finger millet (3.04 and 4.69 t/ha, respectively) due to effective control of weeds as evidenced by lower total weed density and dry weight observed (13.7 no./m2, 8.0 g/m2 at 30 DAS and 23.9 no./m2, 9.0 g/m2 at 60 DAS) along with higher weed control efficiency (92.5–93.2% in 2014 and 93.3–93.8% in 2015) and lower weed index (7.6–10.3%) due to lower number of weed seeds observed during 2014 (12.3, 19.5 and 4.6/kg soil at 15, 30 and 60 days, respectively) and 2015 (11.3, 17.6 and 4.1/kg soil at 15, 30 and 60 days, respectively as compared to minimum tillage (2.60 and 4.03 t/ha, respectively). Whereas, zero tillage has recorded significantly lower grain and straw yield (2.09 and 3.24 t/ha, respectively) due to poor weed control as observed by higher soil weed seed bank. Among different nutrient management practices application of 100% recommended NPK + 7.5 t FYM/ha yielded significantly higher grain and straw yields (3.03 and 4.68 t/ha, respectively) over other nutrient management practices. Wherein, the soil weed seed bank was not significantly influenced by nutrient management practices and their interactions with the tillage.

In search of long-term sustainable tillage and straw mulching practices for a maize-winter wheat-soybean rotation system in the Loess Plateau of China

Development of sustainable agronomic practices and increasing crop water use efficiency (WUE) under the realm of water scarcity and climate change have become the major focuses in the semiarid Loess Plateau region of China. This 7-yr (2001–2007) study investigated the effects of conservation tillage practices and residue management on crop yield, WUE, soil organic carbon (SOC), soil water storage, economic return, and determined the contribution of various environmental factors on crop WUE under a two-year cycle spring maize (Zea mays L.)-winter wheat (Triticum aestivum L.)-summer soybean (Glycine max L.) rotation cropping system. Treatments included conventional tillage (T) as control, conventional tillage followed by straw mulching (TS), no tillage (NT) and no tillage followed by straw mulching (NTS). Averaged over years and species, the overall crop yield was greatest under TS treatment, which was 17 9 and 5% significantly greater than NT, T and NTS treatments, respectively. Additionally, TS treatment resulted in comparable or greater crop WUE than other treatments starting from 2004. Soil moisture storage was not significantly affected by treatments but varied greatly across different soil depths throughout the growing season. Soil organic carbon was significantly increased by straw mulching treatments (NTS and TS) beginning at 2004. In all, NTS treatment provided the greatest economic return on a system basis. Our simulation modeling results indicated that biomass and net radiation are the most important factors in determining WUE in the semiarid Loess Plateau of China.

Effect of Conservation Tillage Practices on Soil Phosphorus Nutrition in an Apple Orchard

Soil phosphorus (P) is an essential and limiting element for plant growth, which is significantly affected by different approaches to soil management. In order to reveal the effect of different management approaches on soil P and phosphatase activity in 0–20 cm and 20–40 cm soil, this research was conducted to study variations in the characteristics of P and phosphatase activity under 3-year tillage without mulching (CK), no-tillage with corn straw mulching (NTSM) and no-tillage with grass (NTG) in Liaoning apple orchard. The results showed that NTSM and NTG could significantly increase soil P content (P < 0.05) as compared with CK. However, the effect was different between NTSM and NTG; with the NTSM approach, the improvement in the P content in 20–40 cm was remarkable, and in the NTG approach, the improvement in the soil surface P content was significant. At the same time, soil phosphatase activity significantly increased (P < 0.05) under NTSM and NTG. The soil surface and 20–40 cm phosphodiesterase (PD) activity was enhanced under the two management approaches, however, the effect of NTG was stronger than NTSM. In addition, NTSM was more conducive to increasing alkaline phosphomonoesterase (AlP), and NTG was more conducive to increasing acid phosphomonoesterase (AcP). Our findings highlight the variation of dominant mechanisms involved in soil P with different mulching materials application. NTSM and NTG could have the potential to increase P content and phosphatase activity, and provide a basis for using this method to improve P phytoavailability and reduce the application of soil fertilizer.

Effects of conservation tillage practices on nodulation of Phaseolus vulgaris roots.

The cost of chemically produced nitrogen fertilizers can be cost prohibitive to farmers. One method of reducing the input of chemically based nitrogen fertilizers is to plant nitrogen fixing cover crops such as the important food crop Phaseolus vulgaris, the common bean. Cover crops also have the benefit of maintaining soil structure and can reduce erosion. The purpose of this study was to determine the effects of conservation tilling practices on nodulation of the common bean. Beans were grown in a randomized control split plot design of Wheat (Control), Rye and Clover (Treatments) utilizing Strip- and No-Till conditions. The beans were planted over the previous season’s cover residue, which grew back during the study. Parameters measured were plant height (cm), leaf area (cm2), damage (%), and number of roots and nodules. Among cover crop plots, there was no difference in mean nodulation of bean plants (P=0.98). A positive correlation was found between nodulation and bean plant height (Wheat: P=0.003, Rye: P=0.01, Clover: P=0.004). In tilling practice, Strip Till was significantly higher in mean nodulation than No Till (P=0.002) and a positive correlation was found between nodulation and plant height in tilling practice (No Till: P=0.004 and Strip Till: P=0.001). Other factors that may interact with nodulation in beans are soil microbe inoculation and existing bacterial communities, root growth habits, soil nutrient content, as well as soil moisture and temperature; however, the importance of these factors may also vary depending upon the species and variety of legume.

The effects of conservation tillage practices and fertiliser management on soil structural properties at an experimental farm

Crop rotation and reduced tillage under conservation agriculture (CA) practices may induce higher soil organic carbon (SOC) and nitrogen (N) levels compared with conventional (Con) tillage practices. Soil organic carbon may increase soil aggregate stability (AS). The study site was a rain-fed CA field trial with a randomised split-plot design. The effects were evaluated over four experimental seasons of CA and Con on AS, SOC, soil N and on temporal trends of soil properties. Soil aggregate samples were taken annually on plots representing two tillage practices and four fertiliser/crop systems. Standard laboratory and statistical procedures were performed to determine soil properties and to test for relationships between soil properties and differences between treatments. Soil aggregate stability significantly (p<0.001) increased from 90 to 140 cm3 as SOC and total N increased from 11.5 to 21.5 g kg−1 and 0.77 to 1.43 g kg−1, respectively. Reduced tillage increased AS and SOC to 126.6 cm3 and 17.2 g kg−1, respectively, compared with Con. Seasonal trends showed increases of AS and SOC under reduced tillage compared with Con, whereas under both tillage practices increasing trends in total and inorganic soil N were observed. Conservation agriculture practices that retain large quantities of crop residues are recommended to enhance AS.