scholarly journals Covariance Structures in Conventional and Organic Cropping Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Abdullah A. Jaradat
Keyword(s):  
Coefficient Of Variation ◽  
Repeated Measures ◽  
Management Practices ◽  
Cropping Systems ◽  
Block Design ◽  
Crop Rotations ◽  
Covariance Structures ◽  
Cumulative Yield ◽  
Temporal Variance

Guidelines are needed to develop proper statistical analyses procedures and select appropriate models of covariance structures in response to expected temporal variation in long-term experiments. Cumulative yield, its temporal variance, and coefficient of variation were used in estimating and describing covariance structures in conventional and organic cropping systems of a long-term field experiment in a randomized complete block design. An 8-year database on 16 treatments (conventional and organic cropping systems, crop rotations, and tillage) was subjected to geostatistical, covariance structure, variance components, and repeated measures multivariate analyses using six covariance models under restricted maximum likelihood. Differential buildup of the cumulative effects due to crop rotations being repeated over time was demonstrated by decreasing structured and unstructured variances and increasing range estimates in the geostatistical analyses. The magnitude and direction of relationships between cumulative yield and its temporal variance, and coefficient of variation shaped the covariance structures of both cropping systems, crop rotations, and phases within crop rotations and resulted in significant deviations of organic management practices from their conventional counterparts. The unstructured covariance model was the best to fit most factor-variable combinations; it was the most flexible, but most costly in terms of computation time and number of estimated parameters.

scholarly journals Microbial Signatures in Fertile Soils Under Long-Term N Management

2021 ◽  
Vol 1 ◽  
Author(s):  
María B. Villamil ◽  
Nakian Kim ◽  
Chance W. Riggins ◽  
María C. Zabaloy ◽  
Marco Allegrini ◽  
...  
Keyword(s):  
Management Practices ◽  
Cropping Systems ◽  
Block Design ◽  
N Fertilization ◽  
Rrna Gene ◽  
Ribosomal Database Project ◽  
Fertilization Rates ◽  
Continuous Corn ◽  
Potential Nitrification

Long-term reliance on inorganic N to maintain and increase crop yields in overly simplified cropping systems in the U.S. Midwest region has led to soil acidification, potentially damaging biological N2 fixation and accelerating potential nitrification activities. Building on this published work, rRNA gene-based analysis via Illumina technology with QIIME 2.0 processing was used to characterize the changes in microbial communities associated with such responses. Amplicon sequence variants (ASVs) for each archaeal, bacterial, and fungal taxa were classified using the Ribosomal Database Project (RDP). Our goal was to identify bioindicators from microbes responsive to crop rotation and N fertilization rates following 34–35 years since the initiation of experiments. Research plots were established in 1981 with treatments of rotation [continuous corn (Zea mays L.) (CCC) and both the corn (Cs) and soybean (Glycine max L. Merr.) (Sc) phases of a corn-soybean rotation], and of N fertilization rates (0, 202, and 269 kg N/ha) arranged as a split-plot in a randomized complete block design with three replications. We identified a set of three archaea, and six fungal genera responding mainly to rotation; a set of three bacteria genera whose abundances were linked to N rates; and a set with the highest number of indicator genera from both bacteria (22) and fungal (12) taxa responded to N fertilizer additions only within the CCC system. Indicators associated with the N cycle were identified from each archaeal, bacterial, and fungal taxon, with a dominance of denitrifier- over nitrifier- groups. These were represented by a nitrifier archaeon Nitrososphaera, and Woesearchaeota AR15, an anaerobic denitrifier. These archaea were identified as part of the signature for CCC environments, decreasing in abundance with rotated management. The opposite response was recorded for the fungus Plectosphaerella, a potential N2O producer, less abundant under continuous corn. N fertilization in CCC or CS systems decreased the abundance of the bacteria genera Variovorax and Steroidobacter, whereas Gp22 and Nitrosospira only showed this response under CCC. In this latter system, N fertilization resulted in increased abundances of the bacterial denitrifiers Gp1, Denitratisoma, Dokdonella, and Thermomonas, along with the fungus Hypocrea, a known N2O producer. The identified signatures could help future monitoring and comparison across cropping systems as we move toward more sustainable management practices. At the same time, this is needed primary information to understand the potential for managing the soil community composition to reduce nutrient losses to the environment.

scholarly journals Maximizing Yields, Nutrient Uptake and Balance for Mustard-Mungbean-T. Aman Rice Cropping Systems through Nutrient Management Practices in Calcareous Soils

2017 ◽  
Vol 9 (9) ◽  
pp. 210 ◽  
Author(s):  
M. A. Quddus ◽  
M. J. Abedin Mian ◽  
H. M. Naser ◽  
M. A. Hossain ◽  
S. Sultana
Keyword(s):  
Nutrient Uptake ◽  
Management Practices ◽  
Nutrient Management ◽  
Crop Yields ◽  
Cropping Systems ◽  
Block Design ◽  
Calcareous Soils ◽  
Cropping System ◽  
Soil Test ◽  
Positive Balance

The experiment was conducted to measure crop yields, nutrient concentration, nutrient uptake and balance by using different nutrient management practices for mustard-mungbean-T. aman rice cropping system in calcareous soil of Madaripur, Bangladesh. Different nutrient management practices were absolute nutrient control (T1); farmer’s practice (T2); AEZ based nutrient application (T3) and soil test based nutrient application (T4). The practices were compared in a randomized completely block design with three replications over two consecutive years. The average yield through application of soil test based nutrient (T4) was showed effective to get highest yields of mustard (1530 kg ha-1), mungbean (1632 kg ha-1) and T. aman rice (4729 kg ha-1). The same practices (T4) exhibited the greatest nutrients uptake by the test crops. The apparent balance of N and K was negative; however it was less negative and less deficiency detect in T4 treatment. Positive balance of P observed in all practices except in T1. There was a positive S balance (7.60 kg ha-1) in T4 but negative in T1, T2 and T3. Zinc balance was found positive in T3 and T4 and negative in T1 and T2. Boron balance in the system was neutral or slightly positive in T1 and negative in T2 but positive in T3 and T4. Organic matter, N, P, S, Zn and B status in soil was improved by T4 treatment. The results suggested that the soil test based nutrient application is viable and sustainable for mustard-mungbean-T. aman rice cropping system in calcareous soils of Bangladesh.

scholarly journals Combined agro-ecological strategies for adaptation of organic horticultural systems to climate change in Mediterranean environment

2016 ◽  
Vol 11 (2) ◽  
pp. 85 ◽  
Author(s):  
Mariangela Diacono ◽  
Angelo Fiore ◽  
Roberta Farina ◽  
Stefano Canali ◽  
Claudia Di Bene ◽  
...  
Keyword(s):  
Crop Production ◽  
Cropping Systems ◽  
Crop Rotations ◽  
Integrated Analysis ◽  
Mediterranean Environment ◽  
Ecological Service ◽  
Conservation Farming ◽  
Ecological Principles ◽  
Set Up

Agricultural biodiversity and related agro-ecological measures could play a crucial role in the agro-ecosystems adaptation to climate changes, thus sustaining crop production. The objective of this study was to assess the suitability (and the best combination) of agro-ecological techniques as potential resilience strategies in organic horticultural systems in a Mediterranean environment. A long-term experimental device called MITIORG (<em>Long-term climatic change adaptation in organic farming: synergistic combination of hydraulic arrangement, crop rotations, agro-ecological service crops and agronomic techniques</em>) is set-up at Metaponto (MT), testing the following agro-ecological measures as well as organic and conservation farming <em>best practices</em>: i) hydraulic arrangement by a kind of ridge-furrow system; ii) cash crop rotations; iii) agro-ecological service crops (ASC) introduction; iv) ASC termination techniques (green manure vs roller crimper); and v) organic fertilisation. The research here reported was carried out during the 2014-2015 season in the MITIORG device, on a rotation of cauliflower (<em>Brassica oleracea</em> L.) and tomato (<em>Solanum lycopersicum</em> L.) crops. A detailed description of the scientific cognitive process that led to setup of the device, its components explanation, as well as preliminary yield results are reported. The outcomes suggest that organic vegetable cropping systems, designed following agro-ecological principles, are able to sustain yield of cash crops in rotation, in spite of changes in temperature and rainfall of the study site. Experimental data available in the next years will allow a deeper integrated analysis of the manifold effects of agro-ecological measures on horticultural systems.

Long-term weed dynamics and crop yields under diverse crop rotations in organic and conventional cropping systems in the Canadian prairies

2016 ◽  
Vol 196 ◽  
pp. 357-367 ◽  
Author(s):  
Dilshan Benaragama ◽  
Steven J. Shirtliffe ◽  
Bruce D. Gossen ◽  
Stu A. Brandt ◽  
Reynold Lemke ◽  
...  
Keyword(s):  
Crop Yields ◽  
Cropping Systems ◽  
Crop Rotations ◽  
Canadian Prairies ◽  
Weed Dynamics

The role of long-term sites in agroecological research: A case study

1995 ◽  
Vol 75 (1) ◽  
pp. 123-133 ◽  
Author(s):  
H. H. Janzen
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Management Practices ◽  
Cropping Systems ◽  
Simulation Models ◽  
Sample Collection ◽  
Productivity Measurement ◽  
Sampling Protocols ◽  
Long Term Studies

Gradual, episodic or subtle changes in agroecosystems can be definitively measured only in long-term studies. The objective of this paper is to illustrate the benefits and limitations of long-term agroecological sites using a crop rotation study (Rotation ABC) established at Lethbridge, Alberta in 1910. Long-term agroecological sites, envisioned as part of a continuum of research levels, seek to determine the persistence of cropping systems with respect to their effects on soil resources and the larger environment. Examples of research findings arising from such sites include the documentation of long-term changes in agricultural productivity, measurement of organic matter changes over time, calculation of long-term nutrient budgets, and verification of simulation models. For example, soil organic matter concentrations in Rotation ABC were found to decline abruptly within the first few decades of cultivation and then approach a new steady state. Despite the continual removal of N in harvested grain, soil N concentrations also appear to have stabilized, suggesting an accession of N approximately equivalent to the amount harvested. Common limitations of long-term sites like that at Lethbridge include: rudimentary experimental design, evolving management practices, incidental changes at the sites, and variation in sampling protocols. The successful use of long-term agroecological sites depends on well-defined objectives, simplicity of design, adequate scale, consistent data and sample collection, and collaboration among sites. The primary justification for the establishment and maintenance of long-term agroecological sites may be their future role in answering questions not yet envisioned. Key words: Soil organic matter, long-term studies, crop rotations, sustainability, fertilizer

scholarly journals Simulating the Long-Term Effects of Fertilizer and Water Management on Grain Yield and Methane Emissions of Paddy Rice in Thailand

Agriculture ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1144
Author(s):  
Nittaya Cha-un ◽  
Amnat Chidthaisong ◽  
Kazuyuki Yagi ◽  
Sirintornthep Towprayoon
Keyword(s):  
Water Management ◽  
Grain Yield ◽  
Management Practices ◽  
Cropping Systems ◽  
Rice Grain ◽  
Management Options ◽  
Irrigated Rice ◽  
Ch4 Emissions ◽  
Rice Cropping Systems

Rice is an important economic crop in Thailand. However, paddy rice fields are one of the largest anthropogenic sources of methane (CH4) emissions. Therefore, suitable crop management practice is necessary to reduce CH4 emissions while rice grain yield is maintained. This study aimed to evaluate appropriate options of fertilizer and water management practices for Thai rice cultivation with regards to improving rice grain yield and reducing CH4 emissions. The Denitrification–Decomposition (DNDC) model was used to simulate grain yield and the emission of CH4 under the three fertilizer options (chemical fertilizer (F), manure (M) and chemical fertilizer + manure (F + M)) with three water management options (continuous flooding (CF), mid-season drainage (MD) and alternate wet and dry (AWD)) during the years 2011–2050. Rain-fed and irrigated rice cropping systems were used. A total of 24 sites distributed in 22 provinces were studied. The data sets of daily climate, soil properties, and rice management practices were required as inputs in the model. Model validation with observation data in a field experiment indicated that simulated grain yields (R2 = 0.83, slope = 0.98, NRMES = 0.30) and cumulative seasonal CH4 emissions (R2 = 0.83, slope = 0.74, NRMES = 0.43) were significantly and positively correlated with the observation. At the end of the simulation period (2046–2050), fertilizer management options of F and F + M gave more grain yield than the M management option by 1–44% in rain-fed rice cropping and 104–190% in irrigated rice cropping system, respectively. Among options, the lower CH4 emissions were found in AWD water management options. The appropriate options with regard to maintaining grain yield and reducing CH4 emissions in the long term were suggested to be F + M with AWD for the rain-fed rice, and F with AWD for the irrigated rice cropping systems.

scholarly journals Labile Soil Organic Matter Pools Are Influenced by 45 Years of Applied Farmyard Manure and Mineral Nitrogen in the Wheat—Pearl Millet Cropping System in the Sub-Tropical Condition

Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2190
Author(s):  
Ranjan Laik ◽  
B. H. Kumara ◽  
Biswajit Pramanick ◽  
Santosh Kumar Singh ◽  
Nidhi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Biomass ◽  
Management Practices ◽  
Microbial Biomass Carbon ◽  
Cropping Systems ◽  
Farmyard Manure ◽  
Mineral N ◽  
N Application ◽  
Tropical Climates

Labile soil organic matter pools (LSOMp) are believed to be the most sensitive indicator of soil quality when it is changed rapidly with varied management practices. In sub-tropical climates, the turnover period of labile pools is quicker than in temperate climates. Organic amendments are of importance in improve the LSOMp for a temperate climate and may be helpful in sub-tropical climates as well. Hence, the status of LSOMp was studied in long term farmyard manure (FYM) amended soils under wheat (Triticum aestivum L.) and pearl millet (Pennisetum glaucum L.) cropping systems in sub-tropical arid conditions. At the same time, we also attempt to determine the impact of mineral nitrogen (N) application in these pools. In this study, dissolved organic matter (DOM), microbial biomass (MB), and light fraction (LF) were isolated in the management practices involving different modes and rates of FYM applications along with the application of nitrogenous fertilizer. C and N contents of the labile pools were analyzed in the soil samples at different periods after FYM applications. Among the different pools, microbial biomass carbon (MBC) and dissolved organic carbon (DOC) were changed significantly with different rates and modes of FYM application and mineral N application. Application of FYM at 15 Mg ha−1 in both the seasons + 120 kg ha−1 mineral N resulted in significantly higher MBC and DOC as compared to all of the other treatments. This treatment also resulted in 13.75% and 5.8% more MBC and DOC, respectively, as compared to the amount of MBC and DOC content in the control plot where FYM and mineral N were not applied. Comparing the labile organic matter pools of 45 years of FYM amendment with initial values, it was found that the dissolved organic carbon, microbial biomass carbon, and light fraction carbon were increased up to the maximum extent of about 600, 1200, and 700 times, respectively. The maximum amount of DOM (562 mg kg−1 of DOC and 70.1 mg kg−1 of DON), MB (999 mg kg−1 of MBC and 158.4 mg kg−1 of MBN), LF (2.61 g kg−1 of LFC and 154.6 g kg−1 of LFN) were found in case of both season applied FYM as compared to either summer or winter applied FYM. Concerning the different rates of FYM application, 15 Mg ha−1 FYM also resulted in a significantly higher amount of DOM, MB, and LF as compared to other FYM rates (i.e., 5 Mg ha−1 and 10 Mg ha−1). Amongst different pools, MB was found to be the most sensitive to management practices in this study. From this study, it was found that the long-term FYM amendment in sub-tropical soil along with mineral N application can improve the LSOMp of the soil. Thus, it can be recommended that the application of FYM at 15 Mg ha−1 in summer and winter with +120 kg ha−1 mineral N can improve SOC and its labile pools in subtropical arid soils. Future studies on LSOMp can be carried out by considering different cropping systems of subtropical climate.

Tillage and cropping effects on soil organic carbon: biodegradation and storage in density and size fractions

2020 ◽  
Author(s):  
Yan Zhang
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Management Practices ◽  
Cropping Systems ◽  
Conventional Tillage ◽  
Plant Residue ◽  
Soil Matrix ◽  
Experimental Treatments ◽  
Plough Layer

&lt;p&gt;Improvements in management practices can prevent the decline of soil organic carbon (SOC) storage caused by conventional tillage&amp;#160;practice in Northeast China. Density and size fractionation can track the transformation of plant residue into SOC and its location&amp;#160;in soil matrix. We used a long-term field study&amp;#160;in China&amp;#160;to evaluate these changes as a result of improved management involving tillage and cropping systems. Experimental treatments included no-till&amp;#160;(NT)&amp;#160;and moldboard ploughing&amp;#160;(MP)&amp;#160;under monoculture maize&amp;#160;(Zea mays&amp;#160;L.) (MM) and maize-soybean (Glycine max Merr.) rotation (MS); these were compared to the traditional management involving conventional tillage&amp;#160;(CT)&amp;#160;under MM. An&amp;#160;incubation&amp;#160;study&amp;#160;was conducted to evaluate mineralization and the biodegradability of SOC. The soils were also physically fractionated by density (light fraction, LF) and size (sand, silt, clay). With improved management, the SOC storage&amp;#160;in the clay&amp;#160;showed the largest increase across&amp;#160;all fractions. This increase was greater for MS than MM. The NTMS treatment resulted in a decline in silt-OC storage compared to CTMM. The&amp;#160;SOC mineralization&amp;#160;(mg CO&lt;sub&gt;2&lt;/sub&gt;-C g&lt;sup&gt;-1&lt;/sup&gt;&amp;#160;soil)&amp;#160;was affected by tillage and driven by LF-OC&amp;#160;and was observed in the order: NTMM&amp;#160;(2.06) &gt; MPMM&amp;#160;(1.72) &amp;#8776;&amp;#160;NTMS (1.71)&amp;#160;&gt;&amp;#160;CTMM (1.52) &amp;#8776;&amp;#160;MPMS (1.41). Both cropping and depth affected the biodegradability of SOC. Considering the plough layer (0-20 cm), treatments under MM had larger proportion of biodegradable SOC than under MS.&amp;#160;We conclude that the significant differences in SOC storage in physical fractions and SOC biodegradation were caused by differences in soil management.&lt;/p&gt;

scholarly journals Weed community structure and soybean yields in a long-term organic cropping systems experiment

Weed Science ◽  
2019 ◽  
Vol 67 (6) ◽  
pp. 673-681 ◽  
Author(s):  
Margaret G. Ball ◽  
Brian A. Caldwell ◽  
Antonio DiTommaso ◽  
Laurie E. Drinkwater ◽  
Charles L. Mohler ◽  
...  
Keyword(s):  
Community Structure ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Nutrient Inputs ◽  
Weed Species ◽  
Soybean Yield ◽  
Weed Density ◽  
Weed Species Richness

AbstractWeed management is a major challenge in organic crop production, and organic farms generally harbor larger weed populations and more diverse communities compared with conventional farms. However, little research has been conducted on the effects of different organic management practices on weed communities and crop yields. In 2014 and 2015, we measured weed community structure and soybean [Glycine max (L.) Merr.] yield in a long-term experiment that compared four organic cropping systems that differed in nutrient inputs, tillage, and weed management intensity: (1) high fertility (HF), (2) low fertility (LF), (3) enhanced weed management (EWM), and (4) reduced tillage (RT). In addition, we created weed-free subplots within each system to assess the impact of weeds on soybean yield. Weed density was greater in the LF and RT systems compared with the EWM system, but weed biomass did not differ among systems. Weed species richness was greater in the RT system compared with the EWM system, and weed community composition differed between RT and other systems. Our results show that differences in weed community structure were primarily related to differences in tillage intensity, rather than nutrient inputs. Soybean yield was lower in the EWM system compared with the HF and RT systems. When averaged across all four cropping systems and both years, soybean yield in weed-free subplots was 10% greater than soybean yield in the ambient weed subplots that received standard management practices for the systems in which they were located. Although weed competition limited soybean yield across all systems, the EWM system, which had the lowest weed density, also had the lowest soybean yield. Future research should aim to overcome such trade-offs between weed control and yield potential, while conserving weed species richness and the ecosystem services associated with increased weed diversity.

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