The Relation With Deep Loosening And Nitrogen To Soil Characteristics And Growth In Maize

Because of unreasonable farming methods in the major maize production area ofnortheast, lead plough layer become shallow, soil plough pan compaction and soil bulkdensity augment. Also reduces the ability of soil to hold moisture and permeable capability.The grow resistance of root increased. Accordingly, the risk of drought, waterlogging, lodgingand inanition in late growth stage was increased and thus affects the improvement of yield.The nitrogenous fertilizer application management was so extensive in the northeast regionthat fertilizer use efficiency is low. The nitrogenous fertilizer application increase rate wasgreater than the maize yield rise rate. In consideration of the premises, we carried outexperiments from2010to2011in the agronomy research base of Yuhong District experimentbase of Shenyang. Experiment with zhengdan958for material, analyzing the soil physicalcharacteristics and maize root with different deep loosening mode. And research the influenceof growth and development in different deep loosening mode and nitrogen management.Through the deep loosening measures to improve nitrogen use efficiency in different nitrogenmanagement, as well as the further research on response of development and increasingproduction mechanism. At the same time, we wanted to provide scientific evidence toresource efficient use and decrease cost of production. The main results were as follows:1. Interleave row deep loosening(T1) and each row deep loosening(T2) can not onlyeffectively break the soil plough pan, but also decrease the volume weight of soil and soildensity in10~30cm. T1with the bigger effect to decrease the volume weight of soil and soildensity than T2. Deep loosening can enhance soil water permeability and capacity on waterdepositing and holding; Due to the soil plough pan, the roots of no-deep loosening(CK) wereconcentrated in0~20cm depth of soil. But the root bleeding intensity of CK was lower thanT1and T2. The maize root in deep loosening treatment not only extent to deepper layer soil,but also expand the scope to plant two sides. In20~50cm depth of soil, the root dry matter,root length density and root surface were bigger in T1and T2than in CK，and T1was biggerthan T2. Deep loosening can reduce the lodging rate and enhance the yield to some extent.Therefore, through interleave row deep loosening(T1) can structure well plough layer and make for maize root fasten and extend in soil and thus absorbed more water and nutrient. T1treatment was with the lower lodging rate and higher maize yield. In the same time, T1treatment could reduce machine power consumption and decrease cost of production than T2.2. Appropriate increase nitrogen application rates can improve light energy useefficiency, decrease respiratory consumption and increase accumulation of photosynthate inmaize leaves. Photosynthetic capacity and light energy use efficiency of maize leaves wereincreased by topdressing nitrogen. Topdressing nitrogen in jointing stage, the photosynthesiswas strongest and light energy use efficiency was highest. The maximum net photosyntheticrate and light saturation point is bigger in deep loosening treatment than that of in non-deeploosening treatment. The trmmol and cond were highest in treatment of nitrogen applicationrates in225kg/hm2and topdressing nitrogen in jointing stage. In this treatment Ci was lowerand Pn was higher than other treatment relatively. In addition combine with interleave rowdeep loosening, the PSII photochemical efficiency was highest.3. Appropriate increase nitrogen application and deep loosening all can improve themaximum leaf area index (LAImax), average leaf area index (MLAI) and high LAI sustaindays. The maximum growth rate of LAI was along with the increase of nitrogen applicationrates. The maximum growth rate of LAI was highest in treatment of nitrogen application ratesin337.5kg/hm~2. Through deep loosening and topdressing nitrogen all can adjust growth rateof LAI, and the effect in deep loosening was bigger than in topdressing nitrogen in earlygrowth period. The topdressing nitrogen treatment was through slow down the decay rate ofLAI to adjust growth rate of LAI in later growth period. Unreasonable nitrogen applicationrates can shorten leaf functional period, and made population photosynthetic potential reduced.Topdressing nitrogen can increase population LAD. The population LAD was highest injointing stage topdressing treatment.4. Stem epidermis thickness, vascular bundle number and area, xylem and phloem areawas strongly inversely associated with lodging.Through deep loosening and appropriate rateof nitrogen all can adjust vascular bundle structure. The big vascular bundle was shaped earlythan small vascular bundle, so topdressing nitrogen in later growth period have less influenceon big vascular bundle. But topdressing nitrogen in later growth period has some facilitation to small vascular bundle increase. However, topdressing nitrogen has less influence on xylemarea of small vascular bundle, but increased the phloem area to some extent. Deep looseningand nitrogen can improve transmission efficiency of vascular bundle, and ensure the "flow"unblocked. Nitrogen content of stem had significantly negative correlated to lodging rate ofmaize. But phosphorus content and potassium content of stem had no significantly negativecorrelated to lodging rate of maize. The flexural strength of stem had negative correlated tolodging rate of maize. Nitrogen application rates in225kg/hm2and topdressing nitrogen injointing stage and combine with interleave row deep loosening treatment is the most rationalcombinations. In this treatment, the vascular bundle internal structure was developed, thetransmission efficiency was highest, the flexural strength was largest, and the rate of lodgingwas lowest.5. Increasing nitrogen application rates appropriately could increase maximum drymatter accumulation rate(Gmax), the time that peak of dry matter accumulation rate curve (Tmax)became short. When the nitrogen application rates in225kg/hm2and topdressing nitrogen injointing stage, the Gmaxwas biggest. Deep loosening could increase Gmax. The increase effectin T1was bigger than in T2. Unreasonable nitrogen application rates had no benefit to grainfilling. In treatment of nitrogen application rates in225kg/hm2, the100-grain weight washighest, maximum dry matter accumulation rate(G-max) and average dry matter accumulationrate(G) was biggest, and the time of maximal filling rate of grains (T-max)emeraged earlier.Topdressing nitrogen in jointing and filling stage and combine with interleave row deeploosening treatment, the100-grain weight was highest and maximum dry matter accumulationrate(G-max) was biggest.6. Nitrogen harvest index and physiological nitrogen use efficiency was decreased underexcessive nitrogen application rates. Although nitrogen transfer from fertilizer to grain ratewas larger in lower nitrogen application rates, but difficult to satisfy the need that yieldincreases. The suitable nitrogen application was helpful to increase fertilizer use efficiencyand crop yield. Nitrogen accumulation and allocation proportion to nutritive organ in matureperiod was increased under excessive nitrogen application rates. But nitrogen allocationproportion to grain was decreased. Topdressing nitrogen can increase the nitrogen percentage in grain to whoil maize plant. Topdressing nitrogen in jointing stage, the yield increase effectsand nitrogen use efficiency were highest, nitrogen redistribution rates and nitrogen invegetative organs contribution rate to grains were biggest. Deep loosening can increase grainyield, nitrogen use efficiency and nitrogen percentage in grain to whoil maize plant in matureperiod to some extent.