Tillage Farming Research Articles

Weed spectrum in different wheat-based cropping systems under conservation and conventional tillage practices in Punjab, Pakistan

Excessive tillage in conventional agriculture has led to soil and environmental degradation. Conservation agriculture (CA) has evolved as an alternate and sustainable crop production system. However, weed control is a serious issue in CA; nonetheless, allelopathy offers a viable option for weed management. This study was conducted to evaluate the shift in weed spectra in different wheat-based cropping systems under different tillage practices in Punjab, Pakistan. Wheat was planted in fallow-wheat, rice-wheat, cotton-wheat, mungbean-wheat and sorghum-wheat cropping systems with zero tillage (ZT), conventional tillage (CT), deep tillage (DT) and CT with beds sowing (BS; 60/30 and 90/45). The most important weeds identified were fat hen, common goosefoot, horseweed, garden spurge, broad-leaved dock, yellow sweet clover, false daisy, salt marsh, rabbit foot grass, bermuda grass, red sprangletop, corn spurry and littleseed canarygrass. Maximum diversity of weeds (number of weed species) was recorded in cotton-wheat under ZT; whereas the sorghum-wheat system had minimum diversity of weeds under DT. Fallow-wheat and mungbean-wheat systems had more grassy and broad leaf weeds, respectively, while sorghum-wheat had less density of these weeds. Likewise, ZT had higher while DT and BS had less density of grassy and broad leaf weeds. However, CT favored some broad leaf weeds like fat hen and common goose foot; DT stimulated only common goose foot; whereas ZT supported some broad leaf and all grassy weeds. Sorghum-wheat system suppressed most of the weeds, grasses in particular, and three grassy weeds (salt marsh, bermuda grass and red sprangletop) were absent owing to its strong allelopathic potential; however, this system favored littleseed canarygrass under ZT. In conclusion, divergent wheat-based cropping systems had different weeds spectra under different tillage practices; and choice of cropping sequence may help suppressing weeds. Inclusion of allelopathic crops, like sorghum, in the wheat-based cropping system may help managing weeds under conventional and conservation tillage practices.

The legacy effect of cover crops on soil fungal populations in a cereal rotation

The use of rotations and minimum tillage in agriculture can permit more sustainable production through increasing soil organic matter and nutrients, and breaking of pathogen lifecycles. Soil fungal populations make an important physical and chemical contribution to soil. For example, mycorrhizal species are important in plant nutrition but are often overlooked when considering management practices for efficient soil function. We undertook DNA metabarcoding (Ion Torrent) using novel PCR primers and high-throughput sequencing of the D1 region of the large ribosomal subunit of the rRNA locus, to assess the effect of different forages and cereal tillage methods on the soil fungal community. The study comprised five forage treatments, perennial ryegrass (Lolium perenne) with either low or high N, chicory (Cichorium intybus), red clover (Trifolium pratense) or white clover (Trifolium repens) grown over 3 harvest years (2010–2012). Cultivation of chicory, red clover or white clover led to significantly divergent soil fungal communities, with a notably lower diversity of fungal populations under clover, suggesting a link to soil N dynamics. Consistent with this, was a negative correlation of soil nitrate-N levels with populations of arbuscular mycorrhizal fungi (AMF) and other root-associated fungal groupings (dark septate endophytes, ‘CHEG’, Sebacinales and Ceratobasidiaceae). In contrast, abundance of Fungi belonging to the genera Mortierella and Cryptococcus were positively correlated with soil nitrate-N, with Mortierella also being negatively correlated with soil P. Spring wheat was sown on the same plots (April 2013) followed by winter barley (October 2013). Half of each plot was sown either after ploughing or by direct drilling. A legacy effect of the preceding forage crop on the fungal community was detected after both cereal crops, with plots previously cultivated with ryegrass being most divergent. No overall effect of establishment method on fungal communities was detected but AMF and CHEG fungi were more abundant on direct-drilled plots and pathogenic fungi were more abundant on ploughed plots after the sowing of winter barley.

Conditions for the adoption of conservation agriculture in Central Morocco: an approach based on Bayesian network modelling

Research in Central Morocco, proves that conservation agriculture increases yields, reduces labour requirements, and erosion, and improves soil fertility. However, after nearly two decades of demonstration and advocacy, adoption is still limited. This paper investigates the critical constraints and potential opportunities for the adoption of conservation agriculture for different typologies of farms. We measured the possible pathways of adoption via a Bayesian decision network (BDN). BDNs allow the inclusion of stakeholders’ knowledge where data is scant, whilst at the same time they are supported by a robust mathematical background. We first developed a conceptual map of the elements affecting the decision about tillage, which we refined in a workshop with farmers and researchers from the Settat area. We then involved experts in the elicitation of conditional probabilities tables, to quantify the cascade of causal links that determine (or not) the adoption. Via BDNs, we could categorise under which specific technical and socio-economic conditions no tillage agriculture is best suited to which farmers. We, by identifying the main constraints and running sensitivity analyses, were able to convey clear messages on how policy- makers may facilitate the conversion. As new evidence is collected, the BDN can be updated to obtain evidence more targeted and fine tuned to the adoption contexts.

Emission estimation of nitrous oxide (N2O) from a wheat cropping system under varying tillage practices and different levels of nitrogen fertiliser

Nitrous oxide is a greenhouse gas with high global warming potential emitted from agricultural sources. The effects of tillage practices and different levels of N fertiliser on seasonal fluxes of N2O were investigated in a field planted with the wheat variety Sonalika. The experiment was conducted during 2012–13 and 2013–14 under conventional tillage (CT) and reduced tillage (RT) farming systems in combination with four different levels of nitrogen fertiliser (i.e. zero nitrogen (F1), 60kgNha–1 (F2), 80kgNha–1 (F3) and 100kgNha–1 (F4)). Both tillage practices and fertiliser significantly (P<0.01) affected seasonal cumulative N2O emissions and wheat yield. However, there was no significant difference in N2O emissions between RTF1 and CTF1 (zero nitrogen). Compared with RT, N2O emission decreased under the CT practice by 2.49%, 10.11%, 7.9% and 27.46% in CTF1, CTF2, CTF3 and CTF4 respectively. Highest and lowest seasonal cumulative fluxes were recorded in RTF4 (N 100kgha–1) and CTF1 (N 0kgha–1) respectively. During the wheat-growing period, nitrogen use efficiency decreased with increasing nitrogen levels and treatment with 60 kg-Nha–1 in the CT practice (CTF2) was found to be effective in increasing nitrogen use efficiency and decreasing yield-scaled N2O emissions.

Towards Conservation Agriculture systems in Moldova

As the world population and food production demands rise, keeping agricultural soils and landscapes healthy and productive are of paramount importance to sustaining local and global food security and the flow of ecosystem services to society. The global population, expected to reach 9.7 billion people by 2050, will put additional pressure on the available land area and resources for agricultural production. Sustainable production intensification for food security is a major challenge to both industrialized and developing countries. The paper focuses on the results from long-term multi-factorial experiments involving tillage practices, crop rotations and fertilization to study the interactions amongst the treatments in the context of sustainable production intensification. The paper discusses the results in relation to reported performance of crops and soil quality in Conservation Agriculture systems that are based on no or minimum soil disturbance (no-till seeding and weeding), maintenance of soil mulch cover with crop biomass and cover crops, and diversified cropping s involving annuals and perennials. Conservation Agriculture also emphasizes the necessity of an agro-ecosystems approach to the management of agricultural land for sustainable production intensification, as well as to the site-specificity of agricultural production. Arguments in favor of avoiding the use of soil tillage are discussed together with agro-ecological principles for sustainable intensification of agriculture. More interdisciplinary systems research is required to support the transformation of agriculture from the conventional tillage agriculture to a more sustainable agriculture based on the principles and practices of Conservation Agriculture, along with other complementary practices of integrated crop, nutrient, water, pest, energy and farm power management.

Why do medium- and large-scale farmers succeed practicing CA and small-scale farmers often do not? – experiences from Paraguay

Conservation agriculture (CA) is defined as a system comprising no or minimum mechanical soil disturbance, permanent organic soil cover, and crop species diversification [FAO. (2014). What is Conservation Agriculture? FAO CA website, consulted on 15.09.2014. Retrieved September 15, 2014, from http://www.fao.org/ag/ca/1a.html]. The vast majority of medium- and large-scale farmers in Paraguay and neighbouring countries (Argentina, Brazil, and Uruguay) who use tractor-based farming systems have moved from conventional agriculture and adopted CA through no-tillage technologies. Among this farmer type, very few wish to return to the old system of tillage agriculture. However, despite massive efforts to transmit the technology to small-scale farmers by development aid projects and local governments, widespread adoption of CA has not happened on farms that use animal traction or manual farming systems; in fact significant dis-adoption of CA practices by smallholders has occurred. Some of the reasons for this dynamic are analysed in this paper. The reasons for dis-adoption by small-scale farmers can be generally divided into two groups. One group has to do with the fact that, comparatively, small-scale farmers are less able to cope with the factors related to CA (e.g. degraded soils, recuperating and maintaining soil fertility and know-how) than medium- and large-scale farmers. The second group of reasons has to do with the approaches and strategies that development aid agencies and local governments have taken towards small-scale farmers, which have influenced small-scale farmers’ ability to adopt and maintain CA practices. Small-scale farmers’ main asset is the soil and the CA/no-tillage system is a knowledge-based, learning-intensive system. However, despite the technical support provided by aid agencies and local governments, small-scale farmers often lack a deeper understanding of the CA concepts and practices. This is attributable to the short- to medium-term and rather conservative transfer-of-technology approaches that have been applied by development aid agency and local government programmes over the years, without any changes and without adaptive research. The latter can be derived, for instance, from the accountability of results to donor agencies or the one-size-fits-all approach applied in order to achieve ‘numbers’. One consequence of this is that ownership by and empowerment of farmers is often absent among dis-adopters. It therefore seems more suitable to apply long term, adaptable approaches to CA with smallholders. The lessons learned in Paraguay may well serve to properly direct future development intervention efforts in this country and also serve to mend development strategies in other countries in South and Central America, Africa or Asia.

Legacy phosphorus and no tillage agriculture in tropical oxisols of the Brazilian savanna

Crop production in the Brazilian Cerrado is limited by soil phosphorus (P) supply without large inputs of inorganic P fertilizer, which may become more costly and scarce in the future. Reducing dependency on fertilizer P requires a greater understanding of soil P supply in the highly weathered soils in this important agricultural region. We investigated the impact of no tillage (NT) and conventional tillage (CT) agriculture on accumulated (legacy) soil P and P forms in four long-term sites. Compared to the native savanna soils, tilled soils receiving regular annual P fertilizer inputs (30–50 kgP ha−1) increased all forms of inorganic and organic P, except highly recalcitrant P associated with the background lithology. However, 70–85% of the net added P was bound in moderately labile and non-labile forms associated with Fe/Al oxyhydroxides rather than in plant available forms. Under NT agriculture, organic P forms and labile and non-labile inorganic P forms were all significantly (P<0.05) increased in the surface soil, except for one site with maize residues where labile inorganic P was increased more under CT agriculture. The contribution of organic P cycling in these tropical soils increased after conversion to agriculture and was proportionally greater under NT. The results highlight the large amounts of unutilized legacy P present in Brazil's Cerrado soils that could be better exploited to reduce dependency on imports of finite phosphate rock. No tillage agriculture confers a positive albeit relatively small benefit for soil P availability and overall soil function.

Air-propelled abrasive grits reduce weed abundance and increase yields in organic vegetable production

Abrasive-weeding is a novel weed management tactic with potential to reduce tillage and hand-weeding in organic agriculture. However, abrasive-weeding has not been tested in vegetable cropping systems and growers are interested in the potential for using organic fertilizers as abrasive grits to control weeds and supplement crop nutrition in one field pass. A two-year field study was conducted at the University of Illinois Sustainable Student Farm to determine the effect of air-propelled abrasive grit type, including organic fertilizers, and application frequency on weed density and biomass and crop yield and marketability in organic tomato (Solanum lycopersicum L.) and pepper (Capsicum annuum L.) cropping systems. Abrasive-grits, including granulated walnuts shells and maize cobs, greensand fertilizer, and soybean meal, were applied via compressed air between one and four times within planting holes of plastic mulch. Weed density was quantified 25 or 37 days after the first application and weed biomass was harvested at the end of the growing season. Tomatoes and peppers were harvested ripe and graded for marketability. Two applications of abrasive grits, regardless of grit type, reduced weed density by 63% and 80% in tomato and pepper, respectively. Broadleaf weeds were more susceptible to abrasive-weeding than grass weeds. Abrasive-weeding reduced final weed biomass by 69–97% compared with the weedy control, regardless of grit type or application frequency. Total tomato yield was up to 44% greater in treated plots compared with the weedy control, whereas total yield gains in pepper (up to 33%) were only approaching significance (p = 0.09). Yield and the marketability of fruit was not negatively affected by grit application, despite minor stem and leaf tissue damage after applications. Organic fertilizers used as abrasive grits in this study could contribute between 35 and 105 kg N ha−1, which may improve the functionality and economic feasibility of abrasive-weeding.

Temporal variability of atmospheric particulate matter and chemical composition during a growing season at an agricultural site in northeastern China

This study presents the observations of PM10 and PM2.5 concentrations at an agricultural site from April to October 2012 in Dehui city, China. Ambient air was sampled by filter-based samplers and online PM monitors. The filter samples were analyzed to determine the abundance of ionic/inorganic elements, organic carbon (OC) and elemental carbon (EC). The daily PM10 concentrations varied significantly over the monitoring period, with an average of 168±63 (in the range of 52–277)μg/m3 during the land preparation/planting period (26 April–15 June), 85±65 (36–228)μg/m3 during the growing season (16 June–25 September), and 207±88 (103–310)μg/m3 during the harvest period (26 September–31 October). PM2.5 accounted for 44%, 56% and 66% of atmospheric PM10 during these periods, respectively. The PM10 diurnal variation showed a distinct peak from 16:00 to 21:00 (LST) during the growing and harvesting seasons, while a gradual increase throughout the daytime until 17:00 was observed during tilling season. Mineral dust elements (Al, Ca, Fe, and Mg) dominated the PM10 chemical composition during the tilling season; OC, NO3−, SO42− and NH4+ during the growing season; and carbonaceous species (i.e., OC and EC) during the harvesting season. Our results indicate that the soil particles emitted by farm tillage and organic matter released from straw burning are the two most significant sources of PM10 emissions contributing to the recurring high pollution events in this region. Therefore, development of agricultural PM inventories from soil tillage and straw burning is prioritized to support air quality modeling.

A comparison of farming practices and performance for wheat production in Haryana, India

An extensive stratified survey was conducted in two different wheat growing seasons in all districts of Haryana (India) to evaluate current agronomic practices and assess performance in wheat production with the purpose of identifying where farmers can make further changes in practices. The survey involved 116 villages (927 farmers) in 2008 and 103 villages (823 farmers) in 2010. Different sized farming operations from each village were surveyed to represent all socio-economic categories of farmers. Agronomic inputs (tillage method, fertilizer practice, variety choice, time of sowing, irrigation, and rotation practice) and yield data are presented as mean data, and individual farmer's information is represented by regression tree (RT) analysis to highlight primary associations between cropping management and wheat yield and the technical efficiency (TE) measure. TE was calculated using the key agronomic variables obtained from the survey, and the farms with the highest TE values were assessed as having the superior ‘best practice’ technology. In the districts where the rice–wheat rotation was adopted, there was an overall higher level of TE. Where rice–wheat rotation is the main cropping practice (for example in Kaithal and Kurukshetra), many of the farmers have adopted zero tillage farming methods, with one third of farmers in Kaithal using zero tillage for planting wheat. In contrast, in Sirsa district where cotton was favoured by the farmers as their monsoon season crop, there were no farms where zero tillage was practised. Also, there was also no zero tillage farming where the pearl millet/cluster bean rotation was used as the monsoon season crop. In most cases farmers use a two applications of nitrogen fertilizer applied post-emergence, particularly in the rice–wheat and cotton–wheat districts. The survey also showed that application of potassium fertilizer and use of zinc is regionally specific and this is consistent with the soil maps that show the potential for deficiency of these nutrients in Haryana districts. Sowing in the rice–wheat districts was mostly at the recommended time in early November. The highest number of irrigations occurred in the districts using the pearl millet–wheat and cluster bean–wheat rotations where sprinkler irrigation is the main application practice. The analysis of TE provides a useful comparison when the 5 different farm size categories are separated. There was no difference in TE with farm size, suggesting the message concerning best practice for wheat production is available to and adopted by farmers irrespective of scale of operation. This analysis highlights where extension messages could be focused, whether for zero tillage in the non-rice districts, management of macro-nutrients, or the targeted use of micronutrients.

Effects of soil management practices on soil microbial communities and development of southern blight in vegetable production

Soil microbial communities and their relationship with major soil factors and disease development under tillage, no-tillage and organic farming practices were studied. Real-time quantitative-PCR (Q-PCR) was performed to quantify soil fungal and bacterial abundance. Length heterogeneity polymerase chain reaction (LH-PCR) combined with cloning and sequencing was used to assess microbial communities. Soil chemical characteristics were significantly different under different management practices. Organic agricultural practice significantly increased soil bacterial and fungal abundances, but not the diversity when compared to tillage and no-tillage management practices. Tillage farming agricultural practice yielded a significant higher bacterial abundance than no-tillage agricultural practice. No difference in fungal abundance was observed between tillage and no-tillage. Bacterial communities in no-tillage and organic cultivation were relatively similar, but significantly different from those in tillage cultivation. Differences of bacterial communities were correlated to soil organic matter (R2=0.558), cation exchange capacity (R2=0.583) and percentage of Mg (R2=0.590). Fungal communities in soil under organic cultivation were significantly different from relatively similar fungal community structure in no-tillage and tillage cultivation treatments. Differences of fungal communities were correlated to soil pH (R2=0.421) and soil organic matter (R2=0.401). In greenhouse assays, severity of southern blight on tomato plants grown in soils collected from the no-tillage was significantly lower than in soils from the tillage field. Different soil management practices have played an important role in altering soil microbial communities and potentially reducing disease incidence of southern blight on tomato.

Low losses of a P and sediment in overland flow suggest that this tillage site and others like it may not be high risk for phosphorous pollution

This trial examined phosphorus (P) loss in overland flow (OLF) at a tillage farm in the southeast of Ireland. The soil was a grey-brown podzolic, and was representative of land covering 16% of the total agricultural area, with tillage practised on approximately one-third of this area. The object of the trial was to establish whether this site is a P-pollution risk to surface water. The productive tillage field was divided into three plots, each of approximately 1ha in size. Plots had low earth dams and open lined drains on the lower boundaries. A flow meter sampler with V-notch tank was connected to each of the three drains. Macro-pore flow (MPF) samplers were installed in the plots. Average depth of overland flow across the three plots was 5.4, 17.5 and 18.1mm y−1 for 2005, 2006 and 2007, respectively. Phosphorus concentration was 1.01, 0.64 and 0.6mg l−1, respectively, and P load was 0.04, 0.11 and 0.18kg ha−1 y−1. The median P concentration in MPF was 1.59mg l−1. Sediment yield (95kg ha−1 y−1) was low compared to that achieved in other studies. No pollution parameter measured represented a serious pollution threat. The results of this study suggest that a large proportion of tillage land in Ireland might be classified as low risk for P loss through the overland flow pathway.

Low losses of a P and sediment in overland flow suggest that this tillage site and others like it may not be high risk for phosphorous pollution

This trial examined phosphorus (P) loss in overland flow (OLF) at a tillage farm in the southeast of Ireland. The soil was a grey-brown podzolic, and was representative of land covering 16% of the total agricultural area, with tillage practised on approximately one-third of this area. The object of the trial was to establish whether this site is a P-pollution risk to surface water. The productive tillage field was divided into three plots, each of approximately 1ha in size. Plots had low earth dams and open lined drains on the lower boundaries. A flow meter sampler with V-notch tank was connected to each of the three drains. Macro-pore flow (MPF) samplers were installed in the plots. Average depth of overland flow across the three plots was 5.4, 17.5 and 18.1mm y 1 for 2005, 2006 and 2007, respectively. Phosphorus concentration was 1.01, 0.64 and 0.6mg l , respectively, and P load was 0.04, 0.11 and 0.18kg ha 1 y . The median P concentration in MPF was 1.59mg l . Sediment yield (95kg ha 1 y ) was low compared to that achieved in other studies. No pollution parameter measured represented a serious pollution threat. The results of this study suggest that a large proportion of tillage land in Ireland might be classified as low risk for P loss through the overland flow pathway.

A Microsimulation Model for Risk in Irish Tillage Farming

Tillage farmers must manage numerous economic risks including uncertain yields and prices. Despite the presence of government payments, these factors can generate a relatively high variability in farm income. The improved management of farm income variability can contribute towards stability in household consumption, support for farm investments, further investment in child education and a reduction in the mental stress associated with variable incomes. In this paper, we develop a new farm-level stochastic microsimulation model to simulate the degree of risk attached to the production of Irelands main tillage grain crop i.e. spring barley for animal feed usage. Forward contracting is the main available risk management tool for Irish tillage farmers. Our microsimulation model is extended in order to estimate the impact of forward contracting on farm income risk. Our results show that forward contracting can reduce farm income risk significantly but that other stable sources of income are probably necessary to contain the exposure to the income risk attached to cereal production. The model is capable of addressing the income risk associated with multiple crops although this version of the model is confined to one particular crop. The model can be further extended to accommodate other risk management tools such as crop insurance or a farm management deposit scheme. This will allow policymakers, farmers and other interested parties to assess the impact of alternative risk management policies on the heterogeneous pool of Irish tillage farmers.

Thoughts on developing small/medium size no-till equipment for conservation agriculture in Asia: summary of post-publication peer review comments.

Traditional agriculture bases most of its operations or practices on soil tillage, which causes likely occurrence of water and soil erosion and sediment runoff. In order to conserve soil, water and environment, Conservation agriculture (CA) is increasingly adopted to replace traditional tillage agriculture to achieve sustainable and profitable agriculture and subsequently improve the livelihoods of farmers. CA holds great potential for all sizes of farms and agro-ecological systems, but its adoption is most urgently required by smallholder farmers, especially those short of laborers. Small/medium size no-till machines and implements are the key to CA adoption. A review article on small/medium size no/minimum-till seeders in Asia published in IJABE triggers a lot of scientific conversation on how to develop suitable no-till equipment among peer experts. This paper presents a collection of these post-publication peer review comments including commentary, questions, answers, suggestions, critical thinking, etc. The authors of the review article also provide response, summary of the review comments and their own standpoints. This open post-publication review and commentary may add value to the published review article and provide new ideas useful for future research and development of CA equipment. Keywords: conservation agriculture, conservation tillage, no-till equipment, post-publication peer review DOI: 10.3965/j.ijabe.20140705.16 Citation: He J, Li H W, Wang Y K, Zhang Z Q, Wang Q J. Thoughts on developing small/medium size no-till equipment for conservation agriculture in Asia: Summary of post-publication peer review comments. Int J Agric & Biol Eng, 2014; 7(5): 139－146.

Influence of physical protectors with different filters on the initial development of Peltophorum dubium (Spreng.) Taub seedlings

The use of physical protectors has been considered as an efficient technique for tillage farming of different species, mainly native ones. Based on the importance of the species, Peltophorum dubium for revegetation of degraded areas, this study evaluated the emergence, survival and initial development of P. dubium seedlings under the influence of physical protectors with different filters. Thus, the following treatments were adopted: absence of physical protector (APP), transparent physical protector (TPP), transparent physical protector + blue cellophane (BPP) and transparent physical protector + red cellophane (RPP). The evaluated characteristics were: emergence velocity index (EVI), seedling survival and emergence percentage, plant height, leaf area and root collar diameter. All of these physical protectors increased the mean values of EVI and survival. In conclusion, the emergence speed and initial development of P. dubium (Spreng.) seedlings grown in the interior of physical protectors, independent on the filters, presented positive results. The reduction on the light intensity interferes positively in the initial growth of these plants. Key words: Native species, reforestation, seedlings.

Carbon dioxide emissions from tillage of two long-term no-till Canadian prairie soils

Agricultural soils under long-term zero tillage (no-till) management have been well known to sequester atmospheric carbon (C) in soil organic matter as well as to reduce emissions of major greenhouse gases. This fact aided the development of the present C offset market around the world and is the basis for no tillage or conservation tillage agriculture as a potential low cost means of reducing greenhouse gas (GHG) emissions. The province of Alberta, Canada currently has C offset protocols under which companies that fail to achieve targeted emission reduction can purchase C credits from agricultural farms that have changed tillage management practices. Our study aimed at quantifying the major GHG carbon dioxide (CO2) emissions from two major agricultural soil types in Western Canada (i.e., Black Chernozem and Gray Luvisol) managed under long-term (∼30 years) no-till after tillage reversal. We also studied the influences of soil temperature and soil moisture, nitrogen (N) fertilization (i.e., no N vs. 100kgNha−1) and inherent soil fertility on the magnitude of tillage reversal impact on soil CO2 emissions. Our study revealed that the CO2 emissions were higher after tillage reversal irrespective of N fertilizer applications, soil types and soil physical environment. Comparative study between historic soil C sequestration after the adoption of long-term no-till and the GHG emissions in the form of CO2 fluxes after tillage reversal on these study plots showed that the short-term rates of C emissions after tillage reversal were higher than the long-term rates of C sequestration. However, since the time scales for comparing the sequestration and emission rates were so different, these results are expected and reasonable. These results, however, indicate that increased soil C storage resulting from changes in agricultural management practices are reversible and that the potential for C sequestration is dependent on the long-term trends of management practices.

Farmers’ Sustainable Strategies for Soil Conservation on Sloping Arable Lands in the Upper Yangtze River Basin, China

The Upper Yangtze River Basin comprises a densely-populated agricultural region with mountainous and hilly landforms. Intensive cultivation has been extended onto steep hillslopes, which constitute the principal source area for sediment production. Soil conservation on sloping arable lands is thus of utmost priority for persisting sustainable agricultural production and maintaining sound ecosystem services. Although there have been many soil conservation techniques, either promoted by the government or adopted by local farmers, the practiced area was very limited relative to the total area affected by soil erosion. This paper attempts to introduce four popular soil conservation measures on sloping arable lands in this region to enhance a broader scale of implementation, including hedgerow buffers, level trenches, sloping terraces and limited downslope tillage. These practices, although developed from local farmers’ indigenous knowledge for productive purposes, have well conformed to our contemporary understanding of soil erosion processes on sloping landscape affected by human disturbances, were of sound suitability to regional manual tillage agriculture and more trade-off-efficient on rill prevention, runoff harvest and nutrient management.

Conservation Agriculture in Zambia: Effects on Selected Soil Properties and Biological Nitrogen Fixation in Soya Beans (Glycine max (L.) Merr)

&lt;p&gt;Conservation agriculture has been promoted in Zambia as a strategy to mitigate some of the negative effects arising from conventional tillage practices. Conservation agriculture offers several potential benefits on soil properties. However, these benefits and impacts vary across agro ecological regions and management practices. This study investigated changes, over time, associated with the practice of conservation agriculture in selected soil chemical, physical and biological properties, including an assessment of the effects on soil respiration, nodulation and biological nitrogen fixation in soya beans (&lt;em&gt;Glycine max &lt;/em&gt;(L.) Merr). Six paired soil samples were collected from conservation agriculture and conventional tillage fields. Fields under conservation agriculture were 4, 7 and 16 years old while those under conventional tillage had been cultivated for over 18 years. Changes in soil properties due to conservation agriculture practice were determined using published laboratory procedures and compared using the paired t-test at 95% confidence level. The results indicated significantly higher soil pH, soil organic carbon, nodulation and biological nitrogen fixation under conservation agriculture than conventional tillage after seven years of practice. The study also showed significantly higher total porosity, soil microbial biomass, soil respiration and lower soil bulk density after sixteen years of practice. Based on these results, the practice of conservation agriculture has potential to improve crop productivity by improving the different aspects of soil fertility, the length of time before this is realized notwithstanding. Further studies that compare several conservation agriculture systems are recommended in other agro-ecological zones of the country to validate these findings.&lt;/p&gt;

Irish farms under climate change – is there a regional variation on farm responses?

SUMMARYThe current paper aims to determine regional impacts of climate change on Irish farms examining the variation in farm responses. A set of crop growth models were used to determine crop and grass yields under a baseline scenario and a future climate scenario. These crop and grass yields were used along with farm-level data taken from the Irish National Farm Survey in an optimizing farm-level (farm-level linear programming) model, which maximizes farm profits under limiting resources. A change in farm net margins under the climate change scenario compared to the baseline scenario was taken as a measure to determine the effect of climate change on farms. The growth models suggested a decrease in cereal crop yields (up to 9%) but substantial increase in yields of forage maize (up to 97%) and grass (up to 56%) in all regions. Farms in the border, midlands and south-east regions suffered, whereas farms in all other regions generally fared better under the climate change scenario used in the current study. The results suggest that there is a regional variability between farms in their responses to the climate change scenario. Although substituting concentrate feed with grass feeds is the main adaptation on all livestock farms, the extent of such substitution differs between farms in different regions. For example, large dairy farms in the south-east region adopted total substitution of concentrate feed while similar dairy farms in the south-west region opted to replace only 0·30 of concentrate feed. Farms in most of the regions benefitted from increasing stocking rate, except for sheep farms in the border and dairy farms in the south-east regions. The tillage farms in the mid-east region responded to the climate change scenario by shifting arable production to beef production on farms.