Effects Of Green Manure In Two Crop Rotation Systems In Weibei Rainfed Highland

In Weibei highland, unfertile soils, limited water resouces and rainfall distribution whichdoes not match crops growth, restrict the improvement of agricultural production. If summerleguminous green manure is introduced to summer fallow-winter wheat rotation system orspring maize-winter wheat ratation system, it will buildup soil fertility and increase cropyields and economic benefits. A field experiment was conducted to study the effect ofdifferent fertilization treatments (CK, no fertilizer; P, P2O540kg/hm2、SP, fertilizer forleguminous corp30kg/hm2) on the growth of leguminous green manure and succeeding crops.Effects of the green manure use methods (Early incorporation, Early mulch, Lateincorporation, No tillage-fallow, Plough-fallow; mulch. incorporation and moved away) oncrop growth, grain yield and soil fertility in the summer green manure-winter wheat croprotation and summer green manure-spring maize-winter wheat rotation systems. Theresults were as below:1. SF treatments had significant higher aboveground biomass of green manure,compared with CK. P fertilizer could increase root biomass of green manure crop. In greenmanure-winter wheat rotation system, SF and P treatments obtained greater succeeding wheatyield, especially when green manure was incorporated into soil half month before wheatsowing.2. In green manure-winter wheat rotation system, early incorporation treatment hadgreater winter wheat tiller number, spike number and wheat yield compared with othertreatments. Early incorporation treatment also increased water content in soil and water useefficiency of wheat compared early mulch and late incorporation. It also had significant effecton increasing soil organic matter, total nitrogen and potassium. Early incorporation of greenmanure is a good choice in green manure-winter wheat rotation system while early mulch hadno advantage.3. In the green manure-spring maize-winter wheat rotation system, mulch treatment hada better soil moisture condition than incorporation treatment and move-away treatment.Total crops yield of mulch treatment and incorporation treatment were slightly higher thanmove-away treatment. Mulch treatment and incorporation treatment tended to increaseorganic matter, labile organic matter and available potassium conten of soil compared with move-away treatment. P treatment had higher bean yield while SP treatment had highermaize yield and wheat yield.4. Two years later, moisture content in soil profile in green manure-spring maize-winterwheat crop rotation system was greater than green manure-winter wheat crop rotation. Therewas no significant difference of soil organic matter, labile organic matter, total nitrogen,available potassium content and pH between two crop rotation systems, indicating that twoseason green manure returning into soil in green manure-winter wheat crop rotation had nosignificant impact on soil fertility, compared with green manure-spring maize-winter wheatcrop rotation system. Soil available phosphorus conten in green manure-winter wheat croprotation was significantly higher than green manure-spring maize-winter wheat crop rotationsystem, probably resulting from activation role of two seasons green manure on soilphosphorus. Compared with green manure-spring maize-winter wheat crop rotation system,nitrate-N accumulation in0-2m soil profile in green manure-winter wheat crop rotation washigher. Also, it had a obviously peak of nitrate-N accumulation in soil profile.The total grainyield in green manure-spring maize-winter wheat crop rotation was higher than greenmanure-winter wheat crop rotation system-(2rotation period) by5849kg/hm2, cost waslower by1619yuan/hm2, and the economic benefit was higher by427.1%.