Guang Wen

Seasonal trends in soil biochemical attributes: Effects of crop management on a Black Chernozem

Knowledge of the response of soil biochemical attributes to crop management and growing season weather is important for assessing soil quality and fertility. Long-term (38–39 yr) crop rotations on a Black Chernozem at Indian Head, Saskatchewan, were sampled (0- to 7.5-cm depth) between early May and mid-October, 11 times in 1995 and 9 times in 1996. We assessed the effect of cropping frequency [fallow–wheat (Triticum aestivum L.) (F–W) vs. F–W–W, vs. Continuous (Cont) W], fertilizers (unfertilized vs. N + P applied), straw harvesting, legume green-manure (GM) in GM–W–W (unfertilized), and legume-grass hay (H) in F–W–W–H–H–H (unfertilized) systems. Changes in organic C and total N (OC, TN), microbial biomass C (MBC), light fraction C and N (LFC and LFN), mineralizable C and N (Cmin and Nmin), and water-soluble organic C (WSOC) were monitored. Organic C and TN were constant and unaffected by rotation phase during the season, but most of the other more labile soil biochemical attributes varied during the sea...

Seasonal trends in selected soil biochemical attributes: Effects of crop rotation in the semiarid prairie

Measurements of seasonal changes in soil biochemical attributes can provide valuable information on how crop management and weather variables influence soil quality. We sampled soil from the 0- to 7.5-cm depth of two long-term crop rotations [continuous wheat (Cont W) and both phases of fallow-wheat (F–W)] at Swift Current, Saskatchewan, from early May to mid-October, 11 times in 1995 and 9 times in 1996. The soil is a silt loam, Orthic Brown Chernozem with pH 6.0, in dilute CaCl2. We monitored changes in organic C (OC) and total N (TN), microbial biomass C (MBC), light fraction C and N (LFC and LFN), mineralizable C (Cmin) and N (Nmin), and water-soluble organic C (WSOC). All biochemical attributes, except MBC, showed higher values for Cont W than for F–W, reflecting the historically higher crop residue inputs, less frequent tillage, and drier conditions of Cont W. Based on the seasonal mean values for 1996, we concluded that, after 29 yr, F–W has degraded soil organic C and total N by about 15% compared...

Effect of rate, frequency and incorporation of feedlot cattle manure on soil nitrogen availability, crop performance and nitrogen use efficiency in east-central Saskatchewan

A study was initiated in 1996 in the Black Soil zone in east-central Saskatchewan to examine soil and crop response to application of feedlot cattle manure at different application rates, frequencies and incorporation timing in a sandy loam and loam soil. Three rates of feedlot cattle manure (approx. 100, 200 and 400 kg total N ha-1) were applied annually and under reduced frequency application regimes. Canola (Brassica napus, L.), spring wheat (Triticum aestivum, L.), hulless barley (Hordeum vulgare, L.) and canola were seeded in spring of 1997, 1998, 1999 and 2000, respectively. Pre-seeding available N (0–60 cm) increased with application rates. Annual application resulted in a linear increase in grain yield with application rates but had no effect on grain N concentration. Cumulative N use efficiency was low (7–10%) with no significant difference among treatments. Single application showed significant residual fertility benefit in the second year but not in the third year except at the high rate. Incor...

Effect of rate, frequency and method of liquid swine manure application on soil nitrogen availability, cropperformance and N use efficiency in east-central Saskatchewan

A study was initiated in the fall of 1996 in the Black soil zone in east-central Saskatchewan (parkland region) to examine the soil and crop response to application of liquid swine manure at different rates, frequencies and methods of application. Low, medium and high rates of liquid swine manure (equivalent to approximately 100, 200 and 400 kg total N ha-1, respectively) were applied annually and in reduced frequency applications using injection and broadcast/incorporated placement over a 4-yr period. Crops grown during this period were Argentine canola (Brassica napus L.) in 1997, hard red spring wheat (Triticum aestivum L.) in 1998, hulless barley (Hordeum vulgare L.) in 1999, and Argentine canola in 2000. Under an annual application regime, a significant elevation of pre-seeding available N in the 0–60 cm soil depth and increased grain yield and protein content with increasing application rates of liquid swine manure were observed. Under a reduced frequency application regime, elevation of pre-seeding...

Comparison of phosphorus availability with application of sewage sludge, sludge compost, and manure compost

Abstract The objectives were to determine if phosphorus (P) from different organic wastes differs in availability to crops. Four materials: digested, dewatered sewage sludge (DSS); irradiated sewage sludge (DISS); irradiated and composted sewage sludge (DICSS); and composted livestock manure (CLM) were applied for two years at five rates (0, 10, 20, 30, 40 Mg#lbha‐1#lbyr‐1) with four replicates. Uptake of P was measured in lettuce [Lactuca saliva L. (cv. Grand Rapids)], bean [Phaseolus vulgaris L. (cv. Tender Green)], and petunia [Petunia hybrida Vilm. (cv. Superior Red)] in 1990, and in consecutively harvested two cuts of lettuce in 1991. Percentage of total P that was extractable by 0.5M sodium bicarbonate (NaHCO3) in CLM (30–70%) was much higher than in DSS, DISS, and DICSS (0.8–5.6%). Phosphorus uptake by crops harvested in an early stage of growth, lettuce in 1990 and first cut lettuce in 1991, and the extractable soil P linearly increased with total P applied. The lack of response in P uptake with b...

Potassium availability with application of sewage sludge, and sludge and manure composts in field experiments

An experiment was conducted to determine the plant availability of K in organic wastes. Four materials: digested sewage sludge (DSS), digested irradiated sludge (DISS), digested, irradiated and composed sludge (DICSS), and composted livestock manure (CLM) were applied to farmland for two years at rates of 10, 20, 30, and 40 mg-solids ha−1 yr−1. Potassium fertilizer (KCl) was added to the control treatment (CT), to which no waste was applied, and to the low-rate waste applications, to meet crop K requirement. Equal yields within different treatments were obtained for the test crops lettuce and snap beans through application of available N at the levels balanced for crop economical production. Potassium from the wastes was evaluated based on the assumption that Crop K uptake/Available K applied was equal between the CT and waste treatments. The results indicated that, in general, K applied with wastes (waste K + fertilizer K) was equally available (101±7%) to fertilizer K (KCl), except for low rate application of DISS (10 Mg ha−1), where the availability of K was low (89±1%).

A yield control approach to assess phytoavailability of Zn and Cu in irradiated, composted sewage sludges and composted manure in field experiments: I. Zinc

The threat of spreading diseases is a serious concern when organic wastes are applied to farmland. Irradiation and composting are effective methods to reduce pathogens. Field experiments were conducted to assess the influence of these pathogen-eliminating methods on plant availability of Zn in the wastes. Four organic wastes: digested and dewatered (DSS), irradiated (DISS), composted (DICSS) sewage sludge and composted livestock manure (CLM) were applied during two growing seasons at 10, 20, 30, and 40 t solids ha−1 year−1. Available N and K in the wastes were estimated and N and K fertilizers were added to the soil to equalize available N and K supply among treatments to avoid dilution of crop Zn concentration. A control treatment (CT) received fertilizers but no waste. Lettuce, snap beans and petunias were grown in 1990, and two cuts of lettuce were harvested in 1991. The influence of waste Zn application on crop Zn concentration was studied within approximately equal crop yields. Crop Zn concentration increased in all crops treated with DSS or DISS, and often reached a maximum at the 30 t ha−1 rate of application, then slightly decreased at 40 t ha−1. The response of crop Zn concentration to the amount of Zn applied in the wastes was best described by quadratic equations. Waste application also significantly increased soil Zn availability index, which was a function of DTPA (diethylenetriamine pentaacetic acid)-extractable soil Zn and soil pH. The index was highly correlated with crop Zn concentration. Although Zn concentration in DICSS was similar to those in DSS and DISS, Zn applied in DICSS did not increase crop Zn concentration or soil availability index. Composting reduced the availability of Zn. The similar concentrations of Zn in DSS and DISS in both years allowed the use of a paired t-test to determine the differences in crop Zn concentration caused by application of DSS and DISS. Zinc applied in DISS produced a higher Zn concentration in bean pods than Zn applied in DSS (t > T0.05 at P < 0.02, df = 15), indicating that irradiation increased phytoavailability of Zn in the sludge. However, no similar effect was found in Zn concentrations in the two cuts of lettuce in 1991 or in soil Zn availability index.

Nitrogen recovery of coated fertilizers and influence on peanut seed, quality for peanut plants grown in sandy soil

ABSTRACT Warm and high precipitation climates in most area of Japan are suitable for growing crops. However, the arable lands are limited. A small scale field experiment was conducted on a sandy soil in the Tottori sand dune to test nitrogen (N)-use efficiency from a regular N fertilizer {ammonium sulfate [(NH4)2SO4]} and a mixture of resin-coated N fertilizers for peanut (Arachis hypogaea L. cv. Hanritusei) production. Nitrogen was applied at 30, 60, 90, and 120 kg N ha−1 for the regular N, and at 60, 90, and 120 kg N ha−1 for the mixture of coated N-phosphorous (P)-potassium (K) 80 days, NPK 140 days and ammonium nitride (NH4NO3) + limestone 120 days, each providing 35, 35, and 30% of N supplied. Sufficient P and K and a micronutrient fertilizer were included. Water was applied through drip irrigation. The seed yields were 81 to 137% higher with the coated N than with the equivalent amounts of regular fertilizer N. Nitrogen recovery rates were 10% to32% for the regular N and 79–94% (average 86%) for the coated N. The high recoveries obtained with the coated N were due to the fact that N release matched crop N uptake and the fertilizer placement (beneath the seeds) allowed for immediate uptake. A highly effective N fertilization management program for crop production on this sandy soil is possible. A carbon (C):N ratio of 16.9 and 13.4 in the seeds was found with the regular N and the high rates of coated N treatments, respectively, indicating the seed quality was significantly affected by N application from the different sources.

Influence of application of sewage sludges, and sludge and manure composts on plant Ca and Mg concentration and soil extractability in field experiments

Application of organic waste influences crop uptake of Ca and Mg and soil extractability, depending on the nature of the crop and the waste. Four organic wastes: (i) digested sewage sludge (DSS), (ii) irradiated sludge (DISS), (iii) composted sludge (DICSS), and (iv) composted livestock manure (CLM) were applied for two years at rates of 10, 20, 30, and 40 Mg solid ha-1 year-1. Fertilizers N and K were applied to the control treatment (CT), as well as to the waste treatments to supplement crop growth across all treatments, so that these nutrients were not treatment variables. Calcium and Mg concentrations in the tissue of lettuce, bean pods and petunias in 1990 and two cuts of lettuce in 1991, and the CH3COONH4-extractable soil Ca and Mg were determined. Concentration of Ca and Mg in bean pods did not change to the waste application. Calcium concentration in bean pods was less than half of that in other crops. Magnesium concentration in bean pods and petunias was same, but was much lower than in lettuce. Application of DSS, in general, increased Ca concentration in the crops more than did other wastes. The extractable soil Ca was positively correlated with Ca applied with DISS (r=0.453, P<0.05). Although only a limited amount of Ca was supplied with CLM at the rate of 10 Mg solid ha-1(40 kg Ca ha-1), Ca concentration in petunias increased significantly, then, decreased with increased Ca application (r=0.453, P<0.05). A similar pattern with CLM was found in the extractable soil Ca. The waste application from all the sources had no influence on crop Mg concentration in 1990, possibly due to low Mg concentration in the wastes. While continuously applied DSS and DISS in 1991 linearly increased Mg concentration in both cuts of lettuce (r=0.867, P<0.01; r=0.670, P<0.01 and r=0.671, P<0.01; r=0.665, P<0.01 for first cut and second cut of lettuce with DSS and DISS application respectively), application of CLM decreased Mg concentration in first cut lettuce. The patterns of extractable soil Mg were opposite to crop Mg concentration, as the extractable soil Mg linearly increased with CLM, and decreased with the high rate of DSS application. The ability of wastes to supply N was an important factor influencing crop Σ cations (K, Ca and Mg) uptake.

A model of oxidation of an elemental sulfur fertilizer in soils

Elemental sulfur (S) fertilizer (S0) has to be oxidized by microorganisms to produce plant available SO4−2-S. This biological reaction is affected by many factors that influence the soil microbial population and activity and is difficult to describe mathematically. In simulating a S0 fertilizer application in the field, we discovered that by adding an exponent (n) to the incubation time (t) of the traditionally accepted first-order equation, the SO4−2-S production could be predicted. The equation that describes this relationship is St = S0 · [1-exp(-kt n)], where St is cumulative SO4−2-S produced from applied S0 at time t, S0 is S0 applied when t = 0, k is the oxidation rate constant, and n is a time function modification factor. The equation was tested in two cultivated chernozemic soils receiving fertilizer-size granule S0 (2.00–3.36 mm diameter) and fine-particle S0 (<44 μm diameter) incubated at 5, 10, and 20 °C at a moisture content of 60% of field water holding capacity. Between 88 and 99% of the variation between predicted and measured SO4−2-S (P < 0.001) was explained, and the predicted values were at a range of 99 to 102% of the measured values with limited variation (SE ≤ 4% of the mean). The modified equation offers a promising tool to predict the available S provided over time based on the amount of S0 fertilizer applied and may have the potential for use in industry and in environmental studies.