Comparative Study on Density Tolerance of Main Varieties in Southwest Maize Zone

This paper conducted a split-plot trial to study the yield,main agronomic characters and density tolerance of 11 maize varieties in southwest maize zone using the density and variety as experimental factors.The results indicated that ① the differences among density,variety and the intersection of density and variety were extremely significant;② Average yield of the tested varieties under high planting density（64 500 plant/hm^2） was significantly higher than that under low-density（49 500plant/hm^2）,and increased 10.37%;③ Four types were selected by the performance of all varieties under high planting density,such as high yield increase with high density,high yield but not increase with high density,low yield increase with high density,low yield but not increase with high density.

Thermal kinetic analysis of a complex process from a solid-state reaction by deconvolution procedure from a new calculation method and related thermodynamic functions of Mn_(0.90)Co_(0.05)Mg_(0.05)HPO_4?3H_2O

Three individual peaks of thermal solid-state reaction processes of the synthesized Mn0.90Co0.05Mg0.05HPO4?3H2O were observed corresponding to dehydration I,dehydration II and polycondensation processes.An alternative method for the calculation of the extent of conversion was proposed from the peak area of the individual DTG peak after applying the best fitting deconvolution function(Frazer–Suzuki function).An iterative integral isoconversional equation was used to compute the values of the apparent activation energy Eαand they were found to be 65.87,78.16 and 119.32 kJ/mol for three peaks,respectively.Each individual peak was guaranteed to be a single-step kinetic system with its unique kinetic parameters.The reaction mechanism functions were selected by the comparison between experimental and model plots.The results show that the first,second and final individual peaks were two-dimensional diffusion of spherical symmetry(D2),three-dimensional diffusion of spherical symmetry(D3)and contracting cylinder(cylindrical symmetry,R2)mechanisms.Pre-exponential factor values of 3.91×106,1.35×107 and 2.15×107 s?1 were calculated from the Eαvalues and reaction mechanisms.The corresponded standard thermodynamic functions of the transition-state(activated)complexes were determined and found to agree well with the experimental data.

Effect of Combined Application of Humic Acid and Urea on the Wheat Growth and Yield

This paper aims to research the effects of combined application of humic acid and urea on the wheat yield and yield component,and establish rational fertilizer application scheme of wheat. Split plot experiment was adopted. Two types of phosphorus fertilizer( adding humic acid or not) was assigned to the main plot,and four types of top dressing modes( different amount of urea and humic acid urea) were used in subplots. Effects of combined application of humic acid and urea on the wheat yield and yield component were researched. 375 kg / ha ordinary DAP + 150 kg / ha urea was used as base fertilizer; topdressing of 300 kg / ha urea humate could effectively promote the plant height,leaf area coefficient and aboveground dry matter amount. Adding humic acid in urea in topdressing significantly enhanced the wheat yield and economic coefficient of wheat. Adding humic acid in urea in topdressing has better effects of yield increasing than base fertilizer,and can be used for large scale extension.

Appraising trapping efficiency of vegetative barriers in agricultural landscapes:Strategy based on a probabilistic approach based on a review of available information

Vegetative barriers have proven their effectiveness in controlling water erosion and enhancing other ecosystem services in agricultural areas.This characteristic has led to the conservation and promotion of vegetative barriers as landscape elements by the Common Agricultural Policy and other policy initiatives.Numerous reviews have dealt with the trapping efficiency of vegetated barriers,although they usually focus on studies from humid climates where their implantation and survival are more favourable.However,vegetated barriers are also an attractive alternative in arid and semi-arid climates.They limit competition for water and nutrients with crops to a reduced area compared to other best management practices,such as cover crops.This study presents a review of trapping efficiency of sediment,runoff,and nutrients(P and N)by vegetative barriers in regions of humid and arid,and semi-arid,climates,and a strategy based on sediment trapping efficiency probability,which in turn is based on the results obtained from our review.Different types of independent variables were grouped and identified for the review:related to the vegetative barrier dimension(buffer width,slope of the plot,and buffer area ratio),and related to the experimental conditions(type of vegetation in the buffer,soil protection of the non-buffered area,type of climate,type of experimental measurement and origin of rainfall).An explor-atory analysis evaluated the significance of the experimental variables,which identified the need to focus on experiments under natural rainfall since those carried out with simulated rainfall presented statis-tically significant differences.In general,average trapping efficiencies for runoff and sediment were 40.1 and 62.6%,respectively.For nutrients,values of trapping efficiencies had an average of 44.9%for phosphorus and 38.4%for nitrogen.Runoff and sediment trapping efficiency in arid and semi-arid re-gions tended to be higher than in humid regions.Regarding dimensional variables,a positive trend was observed in the runoff and sediment trapping efficiency with the width of the vegetative barrier,with a large variability across all the width range.Finally,based on the results of our review,we developed a probabilistic model for sediment trapping efficiency as a normalised cumulative probability distribution function for the two climatic regions separately.Also,we developed it as a function of the width of the vegetative barrier for each climatic region,to facilitate decision-making.This model shows that in 92%of the cases,a vegetative barrier will reduce erosion in humid climates,while this trapping efficiency will be 100%in semi-arid and arid conditions.This analysis showed that vegetative barriers are an alternative to other best management practices,e.g.cover crops,when there are operational or agronomic impedi-ments to their implementation,having a high success rate in reducing erosion in any agricultural area.