Green Fertilizer Research Articles

SIGNIFICANCE OF SOIL DEPTH ON NITROGEN TRANSFORMATIONS IN FLOODED AND NONFLOODED SYSTEMS UNDER LABORATORY CONDITIONS

The influence of different depths of repacked soil cores on changes in N transformation processes was studied with a subtropical semi-arid soil amended with 100 mg N kg-1 of Sesbania green manure (GM) or fertilizer (NH4)2SO4 for 35 days under flooded and nonflooded conditions. Shallow soil depth enhanced the rate of nitrification, particularly where aeration was impeded in flooded soils. However, the opposite occurred for denitrification as the relative predominance of underlying anoxic zone increased with increase in soil depth. Nitrate produced in the thin oxic surface soil layer and overlying water in flooded soils was subsequently lost via denitrification, more rapidly where carbon was supplied by added GM. Decomposition of GM was rapid and apparent recovery of applied 100 mg GM-N kg-1 soil as mineral N after 35 days in flooded soils was 8, 26, 30 and 38% in 1.25-, 2.5-, 5.0- and 7.5-cm deep soil cores, respectively. Soil ammonium-N declined rapidly after an initial rise during decomposition of GM in soil in the shallow soil depth. In contrast, no such decline in NH 4 + -N was observed in deep soil cores. In conclusion, the use of shallow soil depths during laboratory incubations can lead to variable results under flooded conditions. To simulate field conditions for obtaining reliable and quantitative information regarding N transformations in soils under flooded conditions, soil depths of 7.5 cm or greater should be used for laboratory incubations and growth chamber studies.

Effects of Green Manure, Organic Fertilizers and Urea on Yield and Grain Quality of Spring Wheat

Abstract Effects of two green manure crops—persian clover and persian clover/Westerwolth ryegrass—and three fertilizers—liquid manure, meat bone meal and urea-on subsequent spring wheat yields and quality characters were studied in four field experiments. No significant differences between green manure crops in production or effects on wheat were found. The yield was up to 2500 kg/ha higher after the green manure crops than after oats, but the effect on wheat protein content was less pronounced. Fertilization did not increase the yield as much as green manuring, but significantly increased protein content in two of the experiments. In a partial least square regression (PLSR) model, the wheat yield was largely explained by the amount of green manure herbage ploughed in during the autumn and the amount of mineral N in the soil in spring. The prediction model of protein content was weak.

Integrated management of green manure, farmyard manure, and nitrogen fertilizer in a rice‐wheat rotation in northwestern India

Sesbania (Sesbania aculeata) is an important green manure crop for wetland rice, and it can fix large amounts of N2. Farmyard manure (FYM) is traditionally a valuable source of nutrients, but it can meet only a part of the N requirement of the rice crop. Limited information is available on the nitrogen fertilizer value of green manure and complimentary and synergistic effects of green manure, FYM, and nitrogen fertilizer. A field experiment was conducted during 1989–1993 to evaluate the effectiveness of sesbania green manure and FYM (77–105 kg N ha‐1) applied either alone or in combination with green manure for wetland rice. Sesbania accumulated 90 to 135 kg N ha‐1 in 52 days. During each year, the total N addition to green manure and FYM amended plots was adjusted to 150 kg N ha‐1 by applying additional N through urea. The grain yield of rice increased significantly up to 150 kg N ha‐1. Green manure‐N proved as efficient as urea‐N in increasing rice yield. The availability of N from FYM was much lower th...

Reduced chemical input cropping systems in the southeastern United States. I. Effect of rotations, green manure crops and nitrogen fertilizer on crop yields

AbstractInterest in reducing purchased chemical inputs to reduce production costs and avoid possible environmental damage prompted this 7-year study. Two management systems, current management practices (CMP) and reduced chemical inputs (RCI), were evaluated for four crop sequences from 1985 through 1992: continuous grain sorghum; continuous corn; a 2-year rotation of corn and double-cropped winter wheat and soybean; and a 4-year rotation of corn, winter wheat/soybean, corn, and red clover hay (changed in 1989 to a 3-year rotation of corn, red clover hay, and wheat/soybean). No-till planting and recommended rates of fertilizer and pesticides were used in the CMP system. In the RCI system, N was supplied by a crimson clover green manure crop or the red clover in the rotation. Weed control was by chisel plowing, disking, and cultivation.Crimson clover top growth accumulated from 70 to 180 kgN/ha, red clover from 77 to 130 kg N/ha. Rotating crops increased corn yield with CMP but not with RCI. lndry years, corn yields were low (less than 3000 kg/ha), corn did not respond to fertilizer N, and yields generally were higher with CMP than with RCI. With adequate rain, yield of all RCI treatments were the same as yield in CMP continuous corn receiving no fertilizer N. Johnsongrass competition was the main reason for low yields in the RCI treatments. Soybean yields were higher with CMP in 4 years and higher with RCI one year. Wheat and grain sorghum yields were higher with CMP than with RCI. A dramatic decline in johnsongrass in sorghum was noted in 1989, and several plots remained relatively free of johnsongrass through 1992.Management decisions made during the experiment included the degree of input reduction in RCI; whether to either end or modify unproductive treatments; whether to use newly available varieties and pesticides; whether to suspend the experiment to eliminate johnsongrass; and how to add new treatments while retaining the original treatments.

Ecology and Biology of Really Green Fertilizers

Ecology and Biology of Really Green Fertilizers