Decline In Soil Organic Matter Research Articles

SOIL ORGANIC MATTER (SOM): STATUS, TARGET AND CHALLENGES IN NEPAL

Changes in soil organic matter (SOM) are slow and difficult to monitor, usually apparent after few decades. Recent changes in the agriculture had its influence on soil, including the soil organic matter content. About 60% of soil in Nepal now have low organic matter content. Agriculture Perspective Plan (APP) was focused more on the concept of green revolution to increase the chemical fertilizer inputs, however, the scenario is changing. Use of organic fertilizers is promoted extensively by government and different organizations with a target of increasing SOM content from 1.92% in 2015 to 4% by 2035. This paper aims at analysing the current status, targeted goal and the challenges faced in the augmentation of the soil organic matter using data available. Achieving this target requires an addition of extra 2.244 ton/ha of organic matter on a yearly basis for 20 years. The average amount of organic matter (2.5-3 ton/ha) applied is lesser than a single season grain harvest. 4.69% of sites had high soil organic matter in fiscal year 075/76 which slipped to 2.64% in 2076/77. The sites with low soil organic matter increased from 12.73% to 15.31%. The causes behind the SOM decline varies according to different agro-ecological zones like soil erosion, residue burning, imbalanced fertilizer use, defective FYM production etc. Findings suggest precise technologies required to be adopted to tackle with the different niche specific causes of soil fertility decline. Despite the complete nutrient content, bulky nature of organic fertilizers sets a major drawback regarding their transportation, distribution and commercialization. Government of Nepal is promoting organic fertilizer use by subsidizing their production cost by 50%. Following integrated nutrient management (INM) techniques, sustainable soil management practices (SSMP) and promotion of use of locally available resources can play a huge role in making the technology sustainable to the farmers.

Effectiveness of Biopelet Combination of Biochar, Chicken Manure and Fish Waste To Improvement of Chemical Properties of Sandy Soil and Soybean Plant Growth

Most of the activities of the use of organic fertilizers and natural additions of organic matter in agricultural intensification fields in Indonesia have not been able to compensate for the rate of decline in soil organic matter by the decomposition process. Biochar has high C levels and has The mean residence time (MRT) in long period in the soils. It was proven that biochar application may increase soil Carbon but has not been able to increase the production of plant. Therefore the use of biochar combined with organic waste rich in nutrients is important to be developed. The purpose of this study was to determine the effectiveness of some biochar compositions with sugar cane, chicken manure, fish waste in the form of biopelet fertilizer on improving the chemical properties of sandy soils and the vegetative growth of soybean plants. This study used a Randomized Completely Block Design (RCBD) with 2 factors, namely: the first factor (B): the composition of Biochar consisted of 3 levels, namely: 1) 70% biochar, 15% chicken manure, 15% fish waste (B1), 2) 50 % biochar, 25% chicken manure, 25% fish waste (B2), 3) 20% biochar, 40% chicken manure, 40% fish waste and the second factor were (D): The dose of biopelet fertilizers, consists of 4 levels, namely: 1) Control (D0 ), 2) 2.5 tons.ha-1 (D1), 3) 5 tons.ha-1 (D2), 4) 10 tons.ha-1 (D3). The results showed that the addition of biopelet fertilizer can effectively improve soil chemical properties (pH, C-organic, and CEC) and the availability of NPK of the sandy soil. The effectiveness of increasing the N-total of soil varies by an average of 32.42 to 75.79%; followed by available P varies between 17.46 to 40.69%, and Kexch between 8.7 to 25.67%. Improvement of soil chemical properties and the availability of NPK by biopelet fertilizer applications could increase plant growth, but reduce the weight of root nodules.

Nexus Between Crop Residue Burning, Bioeconomy and Sustainable Development Goals Over North-Western India

The crop residue burning in India particularly North-western India is responsible for air pollution episodes and public health concerns; greenhouse gases emissions and radiation imbalance; and declining soil organic matter and soil productivity. The objectives of this paper are to estimate the crop residue burning and emissions from crop residue burning, to recommend interventions in crop residue management and to propose a crop residue management-bioeconomy model incorporating strategies to sustainably manage the crop residues through interventions that enable waste valorization, food and nutritional security, farmers’ livelihood and sustainable agricultural production system. A national inventory on crop residue burning including the pollutant species was prepared using the IPCC methodology. The crop types included for the estimation are cereals, pulses, oilseeds, sugarcane, cotton, jute and Mesta. The total amount of crop residues generated and burned for the year 2017–18 was estimated at 516 million tonnes and 116 million tonnes respectively. It is estimated that 116.3 Tg of crop residues burning released about 176.1 Tg of CO2, 10 Tg of CO, 313.9 Gg of CH4, 8.14 Gg of N2O, 151.14 Gg of NH3, 813.8 Gg of NMVOC, 453.4 Gg of PM2.5, and 935.9 Gg of PM10. The emission estimates can be a proxy to prepare the national level inventory of air pollutant species from crop residue burning. The crop residue management (CRM) demands a transition from the traditional zone of CRM to bioeconomy zone of CRM, wherein the interventions aim at the sustainability of agroecosystem. The proposed bioeconomy model has a four-pronged strategy that includes smart agriculture practices, waste bioeconomy involving aspirational principles of bioeconomy, capacity building of stakeholders’ and proactive government policy. Sustainable agricultural bioeconomy provides ample opportunities to reduce crop residue burning, increase farmers’ livelihood and decarbonize the agricultural production. India’s efforts and policies can provide lessons for other agricultural regions having similar environmental constraints.

Spatial Variations of Vegetation Index from Remote Sensing Linked to Soil Colloidal Status

Recent decades have seen a progressive degradation of soils owing to an intensification of farming practices (weeding and high trafficking), increasing use of pesticides and fertilizers, mainly nitrogen, resulting in a steady decline in soil organic matter, a key component to maintain soil fertility. The work has coupled the normalized difference vegetation index (NDVI) of wheat cultivation in Central Italy to soil properties where the wheat was grown to identify the properties linked to within-field variability in productivity. NDVI was assessed through Copernicus Sentinel-2 (S-2) data during the wheat anthesis phase. The main outcome showed a significant correlation of NDVI variability to soil colloidal status and to the relative quantity in the exchange complex of the Ca2+ ions. No relationship emerged between NDVI and soil macronutrients (nitrogen, phosphorus, and potassium) concentration. The work suggested that such elements (nitrogen, especially) should not be provided solely considering the vegetation index spatial variations. Rational and sustainable management of soil fertility requires the integration of the NDVI data with the whole complex of soil physical/chemical status. In this way, the identification of the real key factors of fertility will avoid the negative impact of overfertilization. As an example, a fertilization plan was simulated for the sunflower–wheat sequence. The results showed that in the study area additional supplies of N and K would be unnecessary.

History and interpretation of early soil and organic matter investigations in Deli, Sumatra, Indonesia

This paper provides a history of the investigation of the soils and organic matter of Deli in Sumatra, Indonesia, for growing tobacco in the early 20th century and an interpretation based on current data, knowledge and understanding. We first review some early chemists and agrogeologists’ investigations on the soils of Deli to increase tobacco production. Van Bemmelen studied the humus of the soil of Deli in 1890 and formalised an 8-year fallow plantation scheme for growing tobacco. While maintaining organic matter had been established, the complexity of soil distribution in the area was more important in determining the quality of tobacco. It took another 40 years for the soil in Deli area to be properly mapped. Jan Henri Druif in the 1930s mapped and classified the soils of Deli based on their parent material and mineralogical composition. We then describe the rise and demise of the tobacco industry from 1930s-current. We examine the implication of the fallow system and soil distribution with the current understanding of soil carbon processes and recent data. The results are interpreted and discussed considering i) the myth of ”poor” tropical soils, ii) nutrient availability after slash and burn, iii) soil organic matter decline after forest conversion and recovery after fallow, and iv) soil mapping and provenance. Based on published studies and observed data coupled with modelling, we attempt to explain early researchers’ observations and deductions. We summarise soil organic carbon dynamic conditions in the tropics after 50 years of forest clearance: under fallow rotation, it is possible to maintain, on average, a constant value of 20% organic carbon (OC) decrease from the original level, while continuous cropping can decrease OC levels up to 30–40%. An extreme condition with continuous cultivation and little organic matter input can result in an OC decline of up to 80%. The historical studies enable to appreciate aspects of soil mapping and organic matter that are repeatedly overlooked in present-day research.

Physical Characteristics of Soil as Influenced by Integrated Organic Nutrient Management Practices - A Review

Sustaining the productivity at higher level to meet the increasing demand of food, fuel and fiber for the growing population is the key issue in Indian agriculture. Among the factors, continuous use of imbalanced fertilizers and decline in soil physical productivity and organic matter are considered responsible. To improve soil physical condition and improve organic matter status of soil, incorporation of organic sources of nutrient in combination with chemical fertilizers are recommended. This review pertinent to the present investigation has been reviewed.

Effectiveness of the combination of biopellet, biochar, chicken manure and fish waste to the improvement of chemical properties of sandy soil and soybean plant growth

Most of the activities of the use of organic fertilizers and natural additions of organic matter in agricultural intensification fields in Indonesia have not been able to compensate for the rate of decline in soil organic matter by the decomposition process. Biochar has a high C level and has the mean residence time in a long period in the soils. It has been proven that biochar applications may increase soil Carbon but have not been able to increase plant production. Therefore, the use of biochar combined with organic waste rich in nutrients is essential to develop. The purpose of this study was to determine the effectiveness of some biochar compositions with sugar cane, chicken manure, fish waste in the form of biopellet fertilizer on improving the chemical properties of sandy soils and the vegetative growth of soybean plants. This study used a completely randomized block design with two factors. The first factor (B) was the composition of biochar consisting of three levels, namely: 70% biochar, 15% chicken manure, 15% fish waste (B1), 50 % biochar, 25% chicken manure, 25% fish waste (B2), and 20% biochar, 40% chicken manure, 40% fish waste (B3). The second factor (D) was the dose of biopellet fertilizers consisting of four levels, namely: control (D0), 2.5 t/ha (D1), 5 t/ha (D2), and 10 t/ha (D3). The results showed that the addition of biopellet fertilizer effectively improved soil chemical properties (pH, C-organic, and CEC) and the availability of N, P, and K of the sandy soil. The effectiveness of increasing the soil total-N varied from 32.42 to 75.79%, P-available varied from 17.46 to 40.69%, and exchangeable K ranged from 8.7 to 25.67%. Improvement of soil chemical properties and the availability of N, P, and K by biopellet fertilizer application increased plant growth but reduced the weight of root nodules.

Identifying potential threats to soil biodiversity.

A decline in soil biodiversity is generally considered to be the reduction of forms of life living in soils, both in terms of quantity and variety. Where soil biodiversity decline occurs, it can significantly affect the soils’ ability to function, respond to perturbations and recover from a disturbance. Several soil threats have been identified as having negative effects on soil biodiversity, including human intensive exploitation, land-use change and soil organic matter decline. In this review we consider what we mean by soil biodiversity, and why it is important to monitor. After a thorough review of the literature identified on a Web of Science search concerning threats to soil biodiversity (topic search: threat* “soil biodiversity”), we compiled a table of biodiversity threats considered in each paper including climate change, land use change, intensive human exploitation, decline in soil health or plastic; followed by detailed listings of threats studied. This we compared to a previously published expert assessment of threats to soil biodiversity. In addition, we identified emerging threats, particularly microplastics, in the 10 years following these knowledge based rankings. We found that many soil biodiversity studies do not focus on biodiversity sensu stricto, rather these studies examined either changes in abundance and/or diversity of individual groups of soil biota, instead of soil biodiversity as a whole, encompassing all levels of the soil food web. This highlights the complexity of soil biodiversity which is often impractical to assess in all but the largest studies. Published global scientific activity was only partially related to the threats identified by the expert panel assessment. The number of threats and the priority given to the threats (by number of publications) were quite different, indicating a disparity between research actions versus perceived threats. The lack of research effort in key areas of high priority in the threats to soil biodiversity are a concerning finding and requires some consideration and debate in the research community.

Use of solid anaerobic digestate and no-tillage practice for restoring the fertility status of two Mediterranean orchard soils with contrasting properties

Soil structure degradation, declining soil organic matter and nutrient losses are among major drawbacks of continuous conventional tillage with large-scale environmental consequences including decreasing soil productivity, groundwater contamination and greenhouse gases emissions. This becomes especially true in conventionally-tilled Mediterranean croplands which are also affected by severe climatic conditions. In this study, a one-year field experiment was carried out to investigate the impact of different tillage practices on the soil fertility status in two tree orchards (olive, citrus) soils with contrasting texture (clay, sandy loam), carbonate content (non-calcareous, slightly calcareous) and pH (strongly acid, slightly alkaline), located in Southern Italy. Treatments included in this study were conventional tillage, conventional tillage combined with the incorporation of solid anaerobic digestate, and no-tillage. Changes in the aggregate stability and dynamics of various C and N pools were assessed by monitoring a large set of physical (aggregate stability index), chemical (pH, electrical conductivity, total organic C, total N, nitrate-N, ammonium-N, total soluble N, extractable organic N), biochemical (microbial biomass C and N, basal respiration, potentially mineralizable N) and eco-physiological (microbial and metabolic quotients, mineralization coefficient) soil variables. Results showed that the stability of soil aggregates declined under conventional tillage, remained unaltered under no-tillage, improved after digestate amendment. Moreover, following incorporation of digestate large and long-lasting increase of the organic pool, microbial C-use efficiency and release of soluble C and N forms were observed in the fine-textured soil. Whereas opposite responses were found in the moderately coarse alkaline soil, where incorporation of digestate stimulated C resources depletion, microbial respiration and N losses due to ammonia volatilization with less beneficial effects on soil organic pools. On the other hand, no-tillage prevented soil C and N resources from over-exploitation (as observed in conventionally-tilled soils) with greater beneficial effects on microbial C-use efficiency and biomass found in the coarse than in the fine-textured soil. Our findings suggest that improved management practices such as no-tillage or conventional tillage combined with incorporation of solid anaerobic digestate should specifically deal with soil and climate conditions to became effective for restoring the fertility status in Mediterranean orchard soils.

No-Till Farming and Conservation Agriculture in South Asia – Issues, Challenges, Prospects and Benefits

Of late, intensive farming for higher food production is often associated with many negative implications for soil systems, such as decline of soil organic matter (SOM), increase in risks of soil erosion by wind and/or water, decline in soil biological diversity, increase in degradation of soil physical quality, lower nutrient-use efficiency, high risks of groundwater pollution, falling water tables, increasing salinization and waterlogging, in-field burning of crop residues, pollution of air and emission of greenhouse gases (GHG), leading to global warming, and decline in factor productivity. These negative implications necessitate an objective review of strategies to develop sustainable management practices, which could not only sustain soil health and ensure food security, but also enhance carbon sequestration, decrease GHG emissions, and offer clean and better ecosystem services. Conservation agriculture (CA), that includes reduced or no-till practices along with crop residue retention and mixed crop rotations, offers multiple benefits. Adoption of a system-based CA conserves water, improves and creates more efficient use of natural resources through the integrated management of available soil nutrients, water, and biological resources, and enhances use efficiency of external inputs. Due to apparent benefits of CA, it is increasingly being adopted and now covers about 180 million hectares (Mha) worldwide. However, in South Asia its spread is low (<5 Mha), mostly concentrated in the Indo-Gangetic Plains (IGP). In this region, one of the serious issues is “residue burning” with severe environmental impacts. A huge amount of crop residue left over after the combine harvest of rice has forced farmers to practice widespread residue burning (∼140 M tonnes) to cope with excessive stubble and also for timely planting/sowing of succeeding crops. In rice-wheat cropping systems, which cover more than 10 Mha in the IGP, CA practices are relatively more accepted by farmers. In these systems, any delay in sowing leads to yield penalty of 1–1.5% per day after the optimum sowing date of wheat. The strong adoption of CA practices in IGP is mainly to overcome delayed sowing due to the field preparation and control of weeds, timely planting, and also escape from terminal heat during the grain-filling stage. Major challenges to CA adoption in South Asia are small land holdings (<1 ha), low technological reach to farmers, nonavailability of suitable farm implements for small farm holders, and the staunch conventional farming mind-set. South Asia region consists of many countries of diverse agro-ecologies with contrasting farming systems and management. This region, recently known for rapid economic growth and increasing population, necessitates higher food production and also hot-spots for adoption of CA technologies. Therefore, in this review critically explores the possibility, extent of area, prospects, challenges, and benefits of CA in South Asia. HIGHLIGHTS Conservation agriculture (CA), consisting of reduced or no-tillage and crop residue retention, is a self–sustainable system which offers an alternative to crop residue burning. The CA approach improves soil health by increasing soil organic carbon (SOC) and aggregation and also conserves soil, water and energy than conventional farming systems. South Asian countries are suitable for adoption of CA practices but the area under CA remains low (<5 Mha) as compared to the global area (180 Mha). Adoption of CA in South Asia has skewed distribution, mainly in Indo-Gangetic Plains (IGP) in India, Pakistan, Nepal and Bangladesh in South Asia. Development of herbicide-resistant weed species and weed shift by continuous application of herbicides are the major challenges in adoption of CA. The traditional-farming mind-set, socio-economic conditions, small farm-holdings, weed and residue management, and non-availability of suitable machinery are key constraints to the low adoption of CA practices in South Asia.

Suppression of amino acid and oligopeptide mineralization by organic manure addition in a semiarid environment

AbstractThe rapid mineralization of organic nitrogen (ON) in semiarid soils frequently results in large N losses, reduced crop yields, and environmental pollution. The addition of manures to soil has the potential to promote microbial growth, increase N immobilization, reverse the decline in soil organic matter, and enhance soil quality. In this study, three contrasting organic manures were used to determine their influences on amino acid and oligopeptide dynamics in soil (as key component of the soil ON‐cycle) as well their effects on the size of the microbial biomass and N immobilization. Laboratory incubation experiments were set up with soil obtained from experimental field trial sites for growing maize. Treatments included soil amended with either poultry manure (PM), farmyard manure, pressmud, or unamended (control). Radio‐ and stable‐isotope (14C–15N) techniques were used to assess ON mineralization, immobilization, and leaching using the amino acids alanine and valine as well as the oligopeptides trialanine and valine–proline–proline as model substrates. Quantitative polymerase chain reaction was used to determine soil bacterial biomass. The results showed that all manures increased microbial growth and total soil amino acids as well as protein content. Greater immobilization and subsequently lower mineralization and leaching were also observed in the manure‐amended soils, with this being most pronounced in the PM treatment. The application of PM also enhanced the half‐lives of the ON compounds in soil and increased the size of the bacterial biomass. Overall, our findings indicate that manure amendments, particularly PM, can help promote more efficient ON cycling in semi‐arid ecosystem by controlling N mineralization, reducing amino acid leaching, and elevating oligopeptide immobilization.

Stakeholder Perspectives to Prevent Soil Organic Matter Decline in Northeastern Italy

A transition from conventional to more sustainable soil management measures (SMMs) is required to reverse the current soil organic matter (SOM) losses in the agroecosystems. Despite the innovations and technologies that are available to prevent SOM decline, top–down knowledge transfer schemes that incentivize a certain measure are often ineffective. Here, we discuss relevant outcomes from a participatory approach where researchers, farmers, practitioners and government officials have discussed opportunities and barriers around SMM application to prevent SOM decline. Within a series of workshops, stakeholders identified, scored, and selected SMMs to field-tests and evaluated the benefits and drawbacks from their application. Results showed that the stakeholders recognized the need for innovations, although they valued the most promising SMM as already available continuous soil cover and conservation agriculture. In contrast, more innovative SMMs, such as biochar use and the variable rate application of organic amendments through precision farming, were the least valued, suggesting that people’s resistance to new technologies is often governed by the socio-cultural perception of them that goes beyond the economic and technological aspects. The valuation of benefits and drawbacks by stakeholders on trialed measures emphasized that stakeholders’ perspective about soil management is a combination of economic, environmental, and socio-cultural aspects, thus corroborating the need for transdisciplinary bottom–up approaches to prevent SOM depletion and increase soil rehabilitation and SOM content.

Effects of Different Organic Amendment Sources on the Physico Chemical Properties of A Nutrient Depleted Vertisol

The decline in soil organic matter, nutrient depletion, and loss of soil fertility due to soil degradation contribute to low agricultural productivity. Organic amend- ments (OAs) have the potentials to reverse soil degradation processes by improv- ing the soil's physical and chemical properties and consequently improve crop growth and yield performance. At Cranfield University, United Kingdom, a greenhouse study investigated the effects of Mushroom Compost, Anaerobic Di- gestate Waste, and Poultry Manure amendments applied at 10 t ha-1 and 30 t ha-1 equivalent rates on the physical and chemical properties of degraded soil. The treatments were laid out in the greenhouse in a completely randomized design replicated four times. The results showed that all the OA treatments significantly increased the soil water holding capacity, total porosity, and significantly reduced bulk density when compared with the un-amended control treatment. Further, the OA treatments showed significant increases in the soil Total-P, Olsen-P, Total-N, total oxides of N, ammonium-N, Available-K, and Available-Mg, relative to the control treatment. The results demonstrate the effectiveness of these OAs in im- proving soils’ physical and chemical properties, and so enhancing soil health and overall ecosystem functioning. The study demonstrated that these OAs improve the physicochemical properties of degraded so

Crop Productivity and Nitrogen Balance as Influenced by Nitrogen Deposition and Fertilizer Application in North China

In spite of the importance of N management in agricultural production, closing the full nitrogen balance remains a challenge, mainly due to the uncertainties in both fluxes of nitrogen input and output. We analyzed N deposition and its influence on crop productivity and field nitrogen balance based on data from three of 15 years (1990–2005) of experiments in North China. The results showed that the average annual nitrogen deposition was 76, 80, and 94 kg N/ha at Changping, Zhengzhou, and Yangling in a wheat-maize rotation system, respectively. The deposited N could support a corresponding total biomass production (wheat plus maize) of 9.6, 10.6, and 8.8 Mg/ha with a total grain yield of 3.8, 4.8, and 3.7 Mg/ha, however, that did not cause a further decline in soil organic matter. N fertilizer application could increase total biomass (grain) by 244% (259%) and 74% (119%) for wheat and maize, respectively. Under optimal N management, N deposition accounted for 17–21% of the total N inputs, which affected significantly the recovery efficiency of applied N. N deposition showed a significant spatial variation in terms of the fraction of dry and wet depositions. On an annual average, N deposition roughly balanced out N losses due to NH3 volatilization and N2O loss from nitrification and denitrification. NH3 volatilization and NO3−-N leaching each accounted for 16–20% of the total N outputs. A system modeling approach is recommended to investigate the spatial variation of N leaching as affected by climatic conditions, and to fully account for the nitrogen fluxes. The N deposition derived from this study can be used as the background N input into the wheat-maize double cropping system for N balance.

Land use land cover changes on soil carbon stock in the Weshem Watershed, Ethiopia

This improper land use extremely affected the Weshem Watershed in Ethiopia. Moreover, land use and land cover changes are linked with human intervention. The human intervention has caused disturbance of the natural ecosystem and decline of soil organic matter (SOM) and soil carbon stock. To under these changes we focused on the effects of the land use/cover changes, on soil carbon stock of the Agricultural land (A), forestland (F), and open grazing land (G) in the Weshem Watershed, Ethiopia over the three decades period of 2001, 2009 and 2017. Using integrated use of Remote Sensing (RS) and Geographic Information System (GIS).Soil samples were taken from each land use from 0-15 cm and 15-30 cm soil depths. Soils physicochemical were determined using standard laboratory procedures. The result showed that from 2001-2017 years forestland area showed an increasing trend as compared the agriculture and open grazing lands. The SOCst in forestland was higher than both agriculture and open grazing lands. Total organic matter and CEC were high and the soil bulk density was low in forestland as compared to other land use types. The highest soil SOCst (9.99 Mg ha-1) value was recorded in forest-to-forest land use changes, and low value of SOCst (5.78 Mg ha-1) was obtained in agriculture land. The lowest SOCst value was in land use changes from agriculture to agriculture.

Yields, Soil Health and Farm Profits under a Rice-Wheat System: Long-Term Effect of Fertilizers and Organic Manures Applied Alone and in Combination

The rice-wheat system (RWS), managed over 10.5 Mha in the Indo-Gangetic Plains of India suffers from production fatigue caused by declining soil organic matter, multi-nutrient deficiencies and diminishing factor productivity. We, therefore, conducted a long-term field experiment (1998–1999 to 2017–2018) in Modipuram, India to study the effect of continuous use of farmyard manure (FYM) as an organic fertilizer (OF), mineral fertilizers applied alone (RDF) and their combination (IPNS), as well as the inclusion of forage berseem (IPNS+B) or forage cowpea (IPNS+C) on crop yield, soil health and profits. The long-term yield trends were positive (p &lt; 0.05) in all treatments except the control (unfertilized) in rice, and the control and RDF in wheat. Although the yields of rice, wheat and RWS were highest under IPNS treatments (IPNS, IPNS+B, IPNS+C), the maximum annual yield increase in rice (9.2%) and wheat (13.7%) was obtained under OF. A linear regression fitted to the yield data under different IPNS options revealed a highly significant (p &lt; 0.001) annual yield increase in rice (5.1 to 6.6%) and wheat (6.8 to 7.7%) crops. Continuous rice-wheat cropping with RDF brought an increase in soil bulk density (Db) over the initial Db at different soil profile depths, more so at depths of 30–45 cm, but inclusion of forage cowpea or berseem in every third year (IPNS+B or C) helped to decrease Db, not only in surface (0–15 cm) but also in sub-surface (15–30 and 30–45 cm depth) soil. Whereas soil organic carbon (SOC) increased under OF, IPNS and IPNS + legume (B or C) treatments, it remained unaffected under RDF after 20 RW cycles. The inclusion of legumes along with IPNS not only helped to trap the NO3–N from soil layers below 45 cm but also increased its retention in the upper soil (0–15 cm depth). On the other hand, RDF had a higher NO3–N content in the lower layers (beyond 45 cm depth), indicating downward NO3–N leaching beyond the root zone. A build-up of Olsen-P was noticed under RDF at different time intervals. The soil exchangeable K and available S contents were maximal under OF and IPNS options, whereas a decline in DTPA extractable-Zn was recorded under OF. Overall, RWS economics revealed that OF treatment involved the maximum cost of cultivation (US$1174 ha−1) with the least economic net return (US$1211 ha−1). Conversely, IPNS + legume (B or C) had lowest cost of cultivation (US$707 to 765 ha−1) and a significantly higher (p &lt; 0.05) net return (US$2233 to 2260 ha−1). The study, thus, underlines the superiority of IPNS over RDF or OF; the inclusion of legumes gives an added advantage in terms of production sustainability and soil health. Further studies involving IPNS ingredients other than FYM is needed to develop location-specific IPNS recommendations.

Hold Your Ground: Threats to Soil Function in Northern Great Plains Grazing Lands

On the Ground • Many soils throughout the northern Great Plains (NGP) of North America possess attributes that support the successful delivery of multiple ecosystem services from grazing lands. • Anticipated changes in climate and land use in the region, however, suggest delivery of these services could be compromised in the future because of an increase in threats to soil function. These threats include soil organic matter decline, reduced physical stability, soil erosion, compaction, localized nutrient accumulation, acidification, and salinization. • Adaptive management to conserve existing soil functions in grazing lands is necessary and includes: 1) judicious management of forage resources, 2) strategic application of management to modify vegetation composition or soil conditions, and 3) use of restoration and conservation practices known to maintain vegetation cover and protect soil. • Management approaches to conserve soil functions in NGP grazing lands will likely require considerable adaptive capacity by land managers. Successful application of management will require timely information about soil and vegetation conditions to guide land-use decisions.

Mitigation of soil loss from turfgrass cultivation by utilizing poultry abattoir sludge compost and biochar on low-organic matter soil

ABSTRACTCommercial turfgrass cultivation is one of the main ornamental industries world-wide; however, successive turfgrass sod cutting from the same site removes surface soil, leading to a decline in soil organic matter, impairment of soil fertility and degradation of environment. The present study was aimed to investigate the applicability of poultry abattoir sludge compost (PASC) and biochar (BC) on the establishment of turfgrass by evaluating plant growth performance and mitigation of soil loss by organic waste amendments. The experimental study was designed on the soil which had originally low-organic matter content and previously used as a turfgrass sod harvested site in a sandy loam soil. Incorporation of PASC to soil improved the physicochemical properties in terms of bulk density (BD), water holding capacity (WHC), cation exchange capacity (CEC), pH, total nitrogen, total organic carbon (TOC), and organic matter (OM) by 37 (±2)%, 45 (±3)%, 55 (±3)%, 21 (±2)%, 48 (±2)%, 90 (±10)%, and 96 (±4)%, respectively. PASC-amended treatments enhanced the turfgrass growth rate more than the BC due to its increased nutrient availability. Incorporation of 100 Mg ha–1 (mega gram per hectare) PASC in surface soil with or without BC decreased the mineral soil removal rate by half of the respective soil (control) treatments. The results of the present study confirmed the utilization of PASC and BC as promising agro-industrial-based fertilizers in turfgrass sod production for sustainable soil and nutrient management.

Dynamics of soil organic carbon following land-use change: insights from stable C-isotope analysis in black soil of Northeast China

Intensive soil tillage is a significant factor in soil organic matter decline in cultivated soils. Both cultivation abandonment and foregoing tillage have been encouraged in the past 30 years to reduce greenhouse gas emissions and soil erosion. However, the dynamic processes of soil organic carbon (SOC) in areas of either continuous cultivation or abandonment remain unclear and inconsistent. Our aims were to assess and model the dynamic processes of SOC under continuous tillage and after cultivation abandonment in the black soil of Northeast China. Soil profiles were collected of cultivated or abandoned land with cultivation history of 0–100 years. An isotope mass balance equation was used to calculate the proportion of SOC derived from corn debris (C4) and from natural vegetation (C3) to deduce the dynamic process. Approximately 40% of SOC in the natural surface soil (0–10 cm) was eroded in the first 5 years of cultivation, increasing to about 75% within 40 years, before a slow recovery. C4 above 30 cm soil depth increased by 4.5%–5% or 0.11–0.12 g·kg−1 on average per year under continuous cultivation, while it decreased by approximately 0.34% annually in the surface soil after cultivation abandonment. The increase in the percentage of C4 was fitted to a linear equation with given intercepts in the upper 30 cm of soil in cultivated land. A significant relationship between the change of C4 and time was found only in the surface soil after abandonment of cultivation. These results demonstrate the loss and accumulation of corn-derived SOC in surface black soil of Northeast China under continuous tillage or cultivation abandonment.

Cover crops in the Southeastern region of Buenos Aires, Argentina: effects on organic matter physical fractions and nutrient availability

In the Southeastern region of Buenos Aires province, soybean monoculture has led to a decline in soil organic matter (SOM) levels in soil, mostly the labile fractions. The reduction of SOM has a negative impact on the soil environment. Cover crops (CC) constitute an alternative to maintain or improve SOM levels. The aim of this study was to determine the effect of oat as CC on (a) the SOM dynamics and (b) the availability of macro- and micronutrients in a representative soil of the Southeastern region of Buenos Aires province. Total organic carbon (TOC) and nitrogen (TON), as well as their labile and mineral-associated fractions, and macro- and micronutrient availability were determined. The treatments were soybean monoculture with and without oat as cover crop. The increases in SOC and TON were 22.7% and 11%, respectively, when CC was included to the soybean monoculture. These increases were observed mostly in the labile fractions, with increases of 61.3 and 38.7% for the particulate coarse organic carbon (PCOf) and particulate fine organic carbon (PCOf), respectively, and 79.2% for the particulate coarse organic nitrogen (NOPg). Regarding the nutrients, an increase of 47.6% was observed in manganese (Mn) in the first 5 cm of soil depth, and a decrease in phosphorous (P) availability in the same soil layer due to its consumption and retention by CC. It can be conclude that CC presented a surface soil effect on the dynamic of SOM, increasing C, N, and available Mn contents, but decreasing soil P availability.