TIME TRENDS IN CROP YIELDS IN LONG-TERM TRIALS

2000 ◽  
Vol 36 (2) ◽  
pp. 165-179 ◽  
Author(s):  
M. J. JONES ◽  
M. SINGH
Keyword(s):  
Time Trends ◽  
Crop Yields ◽  
Linear Time ◽  
Cropping Systems ◽  
Complex Model ◽  
Seasonal Effects ◽  
Yield Data ◽  
Growth Environment ◽  
Over Time

Trends over time in annual crop yields potentially provide measures of the likely long-term sustainability of cropping systems. However, where large annual variability in the growth environment is responsible for most of the large year-to-year yield differences, appropriate analytical techniques must be developed to distinguish real long-term trends from the ‘background noise’. This paper presents models for the estimation of time trends in the yield data from crop rotation systems and discusses the results of applying these models to yield values from two types of long-term trial involving barley, each conducted at two sites in northern Syria.The models used were linear with respect to time (years) and allowed for seasonal effects by means of a quadratic relationship on total rainfall and a linear relationship on planting date. A more complex model might account for more of the variance, but restrictions were imposed by the limited number of degrees of freedom (number of years of data less one) and the choice of meaningful single-valued parameters of growth-season conditions. For many experimental treatments the model accounted for less of the total variance at the wetter site. This may be due to seasonal bufferring by soil moisture stored at depth from one year to the next, and future iterations of the analysis will try to allow for this. The appropriateness of the linear time function is also questioned, and alternative functions will be tested along with alternative structures for plot errors over time.

scholarly journals Geostatistical analysis of crop yield maps in a long term no tillage system

Bragantia ◽  
2010 ◽  
Vol 69 (suppl) ◽  
pp. 9-18 ◽  
Author(s):  
Osvaldo Guedes Filho ◽  
Sidney Rosa Vieira ◽  
Marcio Koiti Chiba ◽  
Célia Regina Grego
Keyword(s):  
Crop Yield ◽  
Crop Yields ◽  
Spherical Model ◽  
Exponential Model ◽  
Spatial And Temporal Variability ◽  
No Tillage ◽  
Yield Data ◽  
The North ◽  
Tillage System

It is known, for a long time, that crop yields are not uniform at the field. In some places, it is possible to distinguish sites with both low and high yields even within the same area. This work aimed to evaluate the spatial and temporal variability of some crop yields and to identify potential zones for site specific management in an area under no-tillage system for 23 years. Data were analyzed from a 3.42 ha long term experimental area at the Centro Experimental Central of the Instituto Agronômico, located in Campinas, Sao Paulo State, Brazil. The crop yield data evaluated included the following crops: soybean, maize, lablab and triticale, and all of them were cultivated since 1985 and sampled at a regular grid of 302 points. Data were normalized and analyzed using descriptive statistics and geostatistical tools in order to demonstrate and describe the structure of the spatial variability. All crop yields showed high variability. All of them also showed spatial dependence and were fitted to the spherical model, except for the yield of the maize in 1999 productivity which was fitted to the exponential model. The north part of the area presented repeated high values of productivity in some years. There was a positive cross correlation amongst the productivity values, especially for the maize crops.

scholarly journals Outcomes of Long-Term Conservation Tillage Research in Northern China

2020 ◽  
Vol 12 (3) ◽  
pp. 1062 ◽  
Author(s):  
Francis Azumah Chimsah ◽  
Liqun Cai ◽  
Jun Wu ◽  
Renzhi Zhang
Keyword(s):  
Crop Yields ◽  
Greenhouse Gas Emission ◽  
Conservation Tillage ◽  
Cropping Systems ◽  
Meta Analysis ◽  
Arable Land ◽  
Aggregate Stability ◽  
Northern China ◽  
Total N

Sustainable food production has long been a priority for mankind and this is being challenged by limited arable land, challenged landscapes, and higher human population growth. China started conservation farming around the 1950’s. However, main Conservation Tillage (CT) research started in 1992. Using a systematic meta-analysis approach, this review aims at examining China’s approach to CT and to characterize the main outcomes of long-term CT research across northern China. Data from organizations in charge of CT research in China showed an improvement in crop yield of at least 4% under double cropping systems and 6% under single cropping systems in dry areas of northern China. Furthermore, long-term CT practices were reported to have improved soil physical properties (soil structure, bulk density, pore size, and aggregate stability), soil nutrient levels, and reduction in greenhouse gas emission. Other benefits include significant increase in income levels and protection of the environment. Limitations to CT practice highlighted in this study include occasional reduction in crop yields during initial years of cropping, significant reduction in total N of soils, increase in N2O emission, and the need for customized machinery for its implementation. Outcomes of CT practice are ecologically and economically beneficial though its limitations are worth cogitating.

scholarly journals Alley Cropping Increases Land Use Efficiency and Economic Profitability Across the Combination Cultivation Period

Agronomy ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 34 ◽  
Author(s):  
Huasen Xu ◽  
Huaxing Bi ◽  
Lubo Gao ◽  
Lei Yun
Keyword(s):  
Land Use ◽  
Crop Yields ◽  
Alley Cropping ◽  
Cropping Systems ◽  
Land Use Efficiency ◽  
Term Experiment ◽  
Long Term Experiment ◽  
Use Efficiency ◽  
Short Term Experiment

Alley cropping allows the famer to effectively use available resources and yield more benefits. Choosing suitable associated crop and mitigating the competition between trees and crops are crucial for designing the alley cropping systems. We conducted a long-term experiment, including apple (Malus pumila)/peanut (Arachis hypogaea), apple/millet (Setaria italica) and apple/maize (Zea mays) alley cropping systems with conventional intercropping distance, and corresponding monocultures (Exp.1), and a short-term experiment with improved intercropping distance in the same three combinations (Exp.2) in the Loess Plateau, China. The results showed crop yields in three alley cropping systems were lower than the corresponding monocultures. Apple yields were significantly constrained by millet and maize in the alley cropping systems, but not sensitive to the presence of peanut. Land equivalent ratios (LERs) ranged from 0.44 to 0.89 before the tree bore fruit. The LERs were greater than 1.0 after the tree bore fruit, and the apple trees made a decisive contribution to the land use advantage. Net present values of three alley cropping systems were on average 60.1% higher than the corresponding monocultures across the alley cropping period. The maximum annual present value in the first–fifth, sixth and seventh–ninth years after the alley cropping establishment was observed in the apple/maize, apple/millet and apple/peanut system, respectively. These results highlight that choosing the optimal alley cropping management and suitable associated crops at different years after establishment may allow farmers to increase the land use efficiency and economic profitability.

Long-term yield patterns in barley-based cropping systems in Northern Syria. 3. Barley monocropping

2000 ◽  
Vol 135 (3) ◽  
pp. 251-259 ◽  
Author(s):  
M. J. JONES ◽  
M. SINGH
Keyword(s):  
Trend Analysis ◽  
Cropping Systems ◽  
Forage Legumes ◽  
Growth Environment ◽  
Individual Enterprise ◽  
Yield Trends ◽  
Bare Fallow ◽  
Protein Output ◽  
Np Fertilizer

Results from monocropped barley treatments in long-term rotation (RTN) and continuous barley (CB) trials at two sites were examined for fertilizer effects on yield means and long-term yield trends. In RTN trials, mean responses to fertilizer (N[ratio ]P2O5) applied annually at rates of 20[ratio ]60 at the drier and 40[ratio ]60 at the wetter site were almost double those from biennial application, confirming the need for annual fertilization in monocropped barley systems. In CB trials, with N and P applied annually in nine factorial combinations, at rates up to 120[ratio ]90, responses to each nutrient were curvilinear and dependent on the presence of the other nutrient. Trend analysis showed a decline in grain yields over time where NP fertilizer had not been applied or applied only at low annual rates (< 60[ratio ]45 or < 60[ratio ]90, according to site); but straw yields, at worst, remained approximately stable in the absence of fertilizer and generally increased strongly with higher NP rates. Uncertainties in the interpretation of trend-analysis results indicate the need for methodology improvements, to include (i) additional single-value parameters of the growth environment, to improve the model's ability to account for seasonal variability, and (ii) a more flexible, non-linear function for time.It was concluded that barley monocropping is not necessarily non-sustainable in the medium term, provided adequate annual fertilization is maintained; but risks of pest or disease build-up, in addition to the superiority of legume-barley systems in biomass and crude protein output demonstrated in preceding papers, undoubtedly favour the introduction of some forage legumes into long-term barley sequences. The most practicable (and acceptable) systems may well be ones in which continuous barley is interrupted by a legume, or even a bare fallow, every third or fourth year. Above all, farmers should be helped to experiment with different forage legumes, barley–legume sequences, and modes of legume harvest, to optimize outputs in relation to their evolving and individual enterprise needs.

Response and adaptation of soybean systems to climate warming in Northeast China: insights gained from long-term field trials

2011 ◽  
Vol 62 (10) ◽  
pp. 876 ◽  
Author(s):  
H. F. Zheng ◽  
L. D. Chen ◽  
X. Z. Han
Keyword(s):  
Global Warming ◽  
Climate Warming ◽  
Crop Yields ◽  
Cropping Systems ◽  
Soybean Seed ◽  
Growing Season ◽  
Yield Reduction ◽  
Seed Filling ◽  
Term Field

Developing and assessing successful strategies to alleviate adverse impact of climate warming presents a new opportunity for sustainable agriculture and adaptation investment. Efforts to anticipate adaptation of cropping systems may benefit from understanding the global warming effects within decades. This study quantitatively examines the temperature warming impacts during, respectively, growing season and seed filling on soybean yields by using data from long-term field fertilisation experiments from 1987 to 2004. Here we report that grain yields significantly decreased with rising temperature during growing season, whereas the effects of increasing temperature at seed-filling stage on crop yields were significantly positive. The results indicate that a further temperature increment during seed filling appears to decrease soybean system’s risk of yield reduction. Importantly, we inferred that earlier occurrence of seed filling would increase the temperature of this period. The implication is that advancing the onset of soybean seed filling could be an effective adaptation option to global warming, providing an average yield benefit of ~14% per 10 days before the present date.

scholarly journals Soil fertility and crop yields in long-term organic and conventional cropping systems in Eastern Nebraska

2011 ◽  
Vol 27 (3) ◽  
pp. 200-216 ◽  
Author(s):  
Sam E. Wortman ◽  
Tomie D. Galusha ◽  
Stephen C. Mason ◽  
Charles A. Francis
Keyword(s):  
Soil Fertility ◽  
Crop Yields ◽  
Cropping Systems ◽  
Animal Manure ◽  
Conventional System ◽  
Organic System ◽  
Organic Systems ◽  
Long Term Study ◽  
Conventional Systems

AbstractOrganic agriculture aims to build soil quality and provide long-term benefits to people and the environment; however, organic practices may reduce crop yields. This long-term study near Mead, NE was conducted to determine differences in soil fertility and crop yields among conventional and organic cropping systems between 1996 and 2007. The conventional system (CR) consisted of corn (Zea maysL.) or sorghum (Sorghum bicolor(L.) Moench)–soybean (Glycine max(L.) Merr.)–sorghum or corn–soybean, whereas the diversified conventional system (DIR) consisted of corn or sorghum–sorghum or corn–soybean–winter wheat (wheat,Triticum aestivumL.). The animal manure-based organic system (OAM) consisted of soybean–corn or sorghum–soybean–wheat, while the forage-based organic system (OFG) consisted of alfalfa (Medicago sativaL.)–alfalfa–corn or sorghum–wheat. Averaged across sampling years, soil organic matter content (OMC), P, pH, Ca, K, Mg and Zn in the top 15 cm of soil were greatest in the OAM system. However, by 2008 OMC was not different between the two organic systems despite almost two times greater carbon inputs in the OAM system. Corn, sorghum and soybean average annual yields were greatest in either of the two conventional systems (7.65, 6.36 and 2.60 Mg ha−1, respectively), whereas wheat yields were greatest in the OAM system (3.07 Mg ha−1). Relative to the mean of the conventional systems, corn yields were reduced by 13 and 33% in the OAM and OFG systems, respectively. Similarly, sorghum yields in the OAM and OFG systems were reduced by 16 and 27%, respectively. Soybean yields were 20% greater in the conventional systems compared with the OAM system. However, wheat yields were 10% greater in the OAM system compared with the conventional DIR system and 23% greater than yield in the OFG system. Alfalfa in the OFG system yielded an average of 7.41 Mg ha−1annually. Competitive yields of organic wheat and alfalfa along with the soil fertility benefits associated with animal manure and perennial forage suggest that aspects of the two organic systems be combined to maximize the productivity and sustainability of organic cropping 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

scholarly journals Soil Fertility Management in Westsik’s Crop Rotation Experiment

2001 ◽  
pp. 34-39
Author(s):  
János Lazányi
Keyword(s):  
Soil Fertility ◽  
Crop Rotation ◽  
Field Experiments ◽  
Crop Yields ◽  
Cropping Systems ◽  
Continuous Production ◽  
Farmyard Manure ◽  
Data Sets ◽  
Soil Fertility Management

The crop rotation experiment, established by Vilmos Westsik in 1929, is the best known and most remarkable example of continuous production in Hungary. It is still used to study the effects of organic manure treatment, develop models and predict the likely effects of different cropping systems on soil properties and crop yields. Westsik’s crop rotation experiment provides data of immediate value to farmers concerning the applications of fertilisers, green, straw and farmyard manure. The experiment also provides a resource of yield, plant and soil data sets for scientific research into the soil and plant processes which control soil fertility, and into the sustainability of production without environmental deterioration. The maintenance of Westsik’s crop rotation experiment can be used to illustrate the value of long-term field experiments.

Long-term behaviour model of skid resistance for asphalt roadway surfaces

2010 ◽  
Vol 37 (5) ◽  
pp. 719-727 ◽  
Author(s):  
Tomas Echaveguren ◽  
Hernán de Solminihac ◽  
Alondra Chamorro
Keyword(s):  
Heavy Traffic ◽  
Realistic Model ◽  
Seasonal Effects ◽  
Skid Resistance ◽  
Heavy Vehicles ◽  
Low Volume Roads ◽  
Equivalence Factor ◽  
Using Data ◽  
Over Time

Skid resistance (SR) is relevant to road safety. Several researchers have showed that SR diminishes its value over time depending on the traffic-aggregated interactions, and the presence of heavy vehicles in the traffic stream. The classical SR model shows that its value drops from a starting value to an equilibrium value over time. However, this behaviour in low-volume roads is not entirely true. In this paper, an SR model in a single mathematic specification is proposed, which considers the polishing effect of heavy traffic through the polishing equivalence factor. The model was calibrated by using data measured with a SCRIM device from 1100 test sections in Chile. Considering speed and temperature factors calibrated for Chile, data were processed and corrected. It was concluded that the model for long-term behaviour of SR is satisfactory, but it is necessary to include the seasonal effects for a more realistic model.

An assessment of the effect of covariances of plot errors over time on the precision of means of rotations with wheat

1997 ◽  
Vol 33 (4) ◽  
pp. 469-475 ◽  
Author(s):  
M. SINGH ◽  
S. CHRISTIANSEN ◽  
B. K. CHAKRABORY
Keyword(s):  
Wheat Yield ◽  
Structure Constant ◽  
Covariance Structure ◽  
Farming Systems ◽  
Standard Errors ◽  
Covariance Structures ◽  
Two Phase ◽  
Yield Data ◽  
Over Time

The introduction of appropriate crop rotations is known to be beneficial in many farming systems. One feature of rotations is that it takes a valuable length of time for the advantage of the rotation to take effect. In long-term rotation trials, the observations from the same plot over years are correlated; ignoring such correlations may affect the precision of the estimates of rotation effects. We examined five covariance structures between the plot errors over time to assess the effect of correlations on the standard errors of rotation means and rotation x cycle combination (interaction) means on wheat yields using eight years of data from six two-phase rotations with wheat. Based on wheat yield data from the four cycles of the rotations considered, the compound symmetry covariance structure (constant correlation) between plot errors arising over alternate years gave more efficient estimates of rotation means compared with the other four covariance structures.

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