Productivity And Resource Utilization In A Forage Canola-winter Wheat Rotation System

The traditional summer fallow system that follows the winter wheat harvest in the Loess Plateau could not only cause a waste of rainfall, light and heat resources, reducing overall resource use efficiency in agricultural systems, but also contributes to a series of environmental problems such as soil erosion. The new forage-canola variety, Siyou1, was introduced into the Loess Plateau rotated with winter wheat, which helps to make full use of water resources, produce forage to fill the needs of development of grassland animal husbandry, and finally leads to improvements on both economic and ecological outcomes. Our study was conducted from2011to2013in the Longdong Loess Plateau, taking four forage canola-wheat rotation systems of Fallow-Winter Wheat-Vetch-Winter Wheat, Fallow-Winter Wheat-Rape-Winter Wheat, Rape-Winter Wheat-Vetch-Winter Wheat and Rape-Winter Wheat-Rape-Winter Wheat as the objects of study, and we examined the biomass outputs of the rotation systems, nutritional values of crop components, and water, nitrogen and land use efficiency, in order to provide scientific basis for Siyou1introduction into the Loess Plateau grassland agricultural system for enhanced productivity and resource utilization. The main results are as follows:1. In2011and2012, Siyou1reached early flowering stage respectively in50days and60days later, when the height was60cm and72cm, dry matter yield was4.78t/hm2and3.98t/hm2, with a crude protein content of23%and20%, the leaf area index was7.7and6.2, the water use efficiency of28kg/m.hm2and23kg/m.hm2, and the nitrogen absorption efficiency was59%and47%. In2011, The0-200cm soil water storage capacity at sowing and harvesting was45%and55%higher compared with the year of2012, indicating that the growth of Siyou1was sensitive to soil moisture and that water content could promote the growth and development of Siyou1.2. The winter wheat following forage canola was managed as dual-purpose to provide grain and forage during2011,2012and2013. The forage yields of Cut1and Cut2under rape-winter wheat were higher than under fallow-winter wheat, whereas forage nutritive values showed no significant difference. As for the rape-winter wheat rotation, the forage yield of Cut2was significantly higher than Cutl. The forage of Cutl and Cut2both had high nutritional value, in which crude protein content was more than20%and RFV was more than151%, however trace-elements level was relatively low. Compared with fallow-winter wheat, the grain yield of winter wheat under rape-winter wheat rotation for Cutl, Cut2and Uncut treatments decreased. Cut2showed significant difference, particularly the numbers of panicles per unit of area were reduced. In the rape-winter wheat rotation system, the grain yields of Cutl and Cut2were lower than Uncut, and generally the yield of Cutl was lower than Cut2. Dual-purpose use of winter wheat for grain and forage in a rotation system sown after forage canola could provide high-quality forage production without significant reductions to grain yield. Spring was the most appropriate time to harvest winter wheat for use as forage under this system.3. The Siyou1could take full advantage of seasonal precipitation, producing a large volume of high-quality forage, largely increasing the output of rotation systems, and have little effect on the following winter wheat yield under sufficient precipitation. Thus the biomass and crude protein production, water use efficiency, nitrogen use efficiency and land use efficiency all expressed as Rape-Winter Wheat-Rape-Winter Wheat> Rape-Winter Wheat-Vetch-Winter Wheat: Follow-Winter Wheat-Rape-Winter Wheat> Follow-Winter Wheat-Vetch-Winter Wheat. The biomass output was17.44t/hm2, the crude protein yield was2.86t/hm2, and water use efficiency and nitrogen uptake efficiency were15.31kg/m.hm2and48.69%respectively under the treatment of Rape-Winter Wheat-Rape-Winter Wheat, which were significantly higher than those of other rotation treatments. The land use efficiency of Rape-Winter Wheat-Rape-Winter Wheat reached1.28, which was optimum rotation of forage canola-winter wheat rotations.