Plant Response to Organic Amendments and Decreasing Inorganic Nitrogen Rates in Soils froma Long‐Term Experiment

Abstract

To decrease the potential for adverse environmental impacts of N in agroecosystems, there is increasing emphasis on improving N efficiency of organic and inorganic sources. Greater reliance on organic N sources can cause short‐term crop yield decreases. Consequently, a study was conducted to determine the effect of decreasing rates of inorganic N during a transition from inorganic to organic N sources. The approach was to grow four crops of maize (Zea mays L.) during a period of 306 d in the greenhouse on soils that varied widely in organic matter and biological activity because of long‐term residue and fertilizer management. Treatments were arranged as a complete factorial with the following factors: four soils obtained from the Residue Utilization Plots (RUP), Columbia Basin Research Center, Pendleton, OR (beef manure or pea [Pisum sativum L.] vine residue, 0 or 90 kg N ha−1, applied biennially since 1931); four greenhouse amendments (pea vine, composted beef or poultry manure, or control); and four rates of N fertilizer (0–1600 mg N [2 kg]−1 soil as NH4NO3). In the absence of organic residue or N fertilizer, soil from the manure RUP produced greater dry matter yield (DMY) and plant N uptake than soil from the other RUP treatments. There was no net N mineralization from beef manure added in the greenhouse. Between 10 and 30% of the total poultry manure and pea vine N added was taken up by the four maize crops. Results showed that, by the fourth crop, when inorganic N applications had decreased to zero, plant productivity by organic residues was best maintained by pea vine residue or poultry manure.

Crops use-efficiency of nitrogen from manures permitted in organic farming

“…In comparison with AN, the CM showed a complete incapacity to provide enough N for maize, the first crop after manure application in the pot experiment. Low apparent N recoveries of farmyard manures are the results usually found in previous studies (Rodrigues et al, 2001;Paul and Beauchamp, 1993;Beauchamp, 1986;Baldock and Musgrave, 1980;Fauci and Dick, 1994).…”

“…Douglas and Magdoff (1991), working with 19 different organic residues, concluded that organic substrates with C:N ratios between 11 and 25 are usually found to result in net N mineralization. Other studies have shown that apparent N recovery from manures is usually low (Beauchamp, 1986;Paul and Beauchamp, 1993;Fauci and Dick, 1994;Rodrigues et al, 2001). However, Veg showed a long period of apparent net N immobilization which is not usual.…”

Residual effect of nutrient integration on some selected soil chemical properties of the guinea savanna agro-ecological zone of Nigeria.

“…Eghball, (2002) also reported higher SOM with application of compost than with non -composted treatments. The trend observed for soil nitrogen and phosphorus was similar to that of SOM, the positive influence of combined poultry manure + NPK 20 -10 -10 and cowpea (ITAS EARLY) had on soil nutrient dynamics corroborates the results reported by Owaiye (1993); Fauci and Dick (1994) and Eghball, (2002). This seems to suggest that SOM is paramount in sustaining other soil quality factor (Robinson et al, 1994).…”

Trends of lettuce and carrot yields and soil enzyme activities during transition from conventional to organic farming in an Andosol

“…In this study, commercial organic fertilizer, poultry manure and fish meal were used for organic treatment. Instantaneous efficiency -that is, rapid mineralizationof these organic materials might be a reason for the short period of low yield (Bitzer and Sims 1988;Fauci and Dick 1994a;Hartz and Johnstone 2006) and/or a reason why N uptake was not a factor responsible for the low yield of organic carrots. Relatively high soil N availability in the experimental field might be another reason for it (Fig.…”