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CULTIVATION OF INDUSTRIAL CROPS AS A RENEWABLE RESOURCE ON LOWLAND MOORS - G. Schalitz[15], M. Fechner[16], A. Behrendt[17] and K.-D. Robowsky[18]


SUMMARY

Uncultivated grassland sites in northeastern Germany are to a large degree, suitable for the cultivation of industrial crops as renewable resources. This is due to the inflow of external water into the area. On lowland moor native Phalaris arundinacea showed the best adaptation to the site, with a high yield and good harvesting potential. Plant available mineral nitrogen in peat soils is due to the process of mineralization. Most of this is taken up by Phalaris and so does not, therefore, enter the groundwater. Miscanthus has a high winter mortality level and for this reason is not viable for cultivation. Miscanthus favours humus covered mineral soils, with a low groundwater table (90 cm). It produces here the highest yields by efficient water utilization. Miscanthus nitrogen requirement is lower than that of Phalaris.

Keywords: industrial crops, lowland moor, nutrient balance, water balance, yield

INTRODUCTION

Previous studies have hardly considered uncultivated grassland sites as a source of renewable resources. Grass moorland, however, may have a particular potential for the cultivation of some industrial crops, due to the high level of organic substances present and the inflow of external water. In any case it is more useful for the land to be highly productive than to be drained or left fallow. If the latter is the case, a tall herb community will develop which loosens the soil and greatly reduces its nitrogen supply (Schalitz et al., 1996). As large areas of arable land in eastern Germany are no longer or only partially in use, there is immediate potential for the establishment of industrial crops. This would also provide a new source of income for farmers.

MATERIALS AND METHODS

Industrial crop species were tested at the low moor site at Paulinenaue, northwest Berlin. Both lysimeter and field experiments were undertaken. In the lysimeter study groundwater lysimeters with a surface area of 1 m² were used. Groundwater levels were set at a fixed height and then excess water added to simulate input into the catchment area (Behrendt et al., 1993).

Field experiments concentrated on the crops' viability for cultivation and their potential yield. Phalaris arundinacea and Miscanthus sinensis were grown both in a humous deep sand layer soil type and in shallow moor soil. Both soils have been influenced by the groundwater. Fertilizer was administered using a two factor strip layout. Each test was replicated three times.

RESULTS AND DISCUSSION

Water balance

Water consumption was found to be higher in plots with a high water table (50 cm) than in those with lower (90 cm) water levels. On sand humus gley, consumption by the native Reed Canary-grass (Phalaris arundinacea) was higher than by Miscanthus (1992-1995 918:624 mm).

The soil type is of particular importance when comparing Phalaris and Miscanthus. Due to the poor development and low biomass of Miscanthus sinensis var. giganteus, its water demand was unusually low on the moor soil. Therefore, a true comparison is only possible between the crops grown on sand humus gley. These trials clearly show that Miscanthus requires less water than Phalaris. Miscanthus is therefore able to survive in areas of lower precipitation, with only 600 mm per year rainfall (Dingebauer et al., 1992). Jacks-Sterrenberg (1995) found that for 25-30 mm ha-1 Miscanthus, 625-780 mm a-I rainfall is required. When a nitrogen fertilizer was applied, absolute water consumption rose. This was due to the increased biomass stimulated by the fertilizer, which in turn led to increased transpiration. However, when the specific water consumption usually fell, water utilization was improved.

A particularly strong reaction to the nitrogen fertilizer was shown by Reed Canary-grass in the field. Thus, the specific water consumption of Reed Canary-grass was consistently lower on the moor soil than on sand humus gley. This result demonstrates a particularly good adaptation to this site. Given the fact that Miscanthus does not produce enough biomass, it is not possible to calculate a meaningful specific water demand quotient. On sand humus gley, Miscanthus had a low specific water demand, which is typical for a C4 plant. Thus, Miscanthus produced a high yield on this soil (Table. 1).

Nutrient balance

When good stands of Phalaris developed, the nitrogen balance on moor soil was apparently negative. Phalaris, as a nitrogen loving plant, removes a noticeable quantity of nitrogen from the soil. Without the addition of 100 kg ha-1 nitrogen fertilizer, the nitrogen level would have fallen further. Applying 100 kg ha-1 leads to a nominal rise in N03 in the groundwater only. As Phalaris is able effectively to utilize 300 kg/ha N, it is not surprising that a negative nitrogen balance was shown for this fertilizer level. On sand humus gley, however, the balance was positive at 100 kg ha-1 N (lower yield!), introducing the possibility of dangerous levels of N03 in the groundwater.

Miscanthus grown without nitrogen fertilizer displayed a negative balance both on the moor soil and on sand humus gley. At a nitrogen level of 100 kg ha-1 a strong positive balance was shown, demonstrating the fact that Miscanthus extracts less nitrogen from the soil than Phalaris. The amount of fertilizer (100 kg N ha-1) used was obviously too high on both sites, as the plants were unable to utilize all the nitrogen available.

A positive potassium balance was shown by all plants on all soils types receiving constant doses of potassium fertilizer. Phalaris grown on moor soil extracted most of the potassium from the soil. The results from all species and sites underline the need for a regular potassium supply, for both peat and sandy soils. The sand humus gley site experiences strong leaching of nutrients and so an addition of fertilizer is also important here.

Table 1. Dry mass yield (kg/m²) obtained in the lysimeter experiments, Paulmenaue 1992-1995.


Lowland Moor

Sand Humus Gley

GW 50 cm

GW 90 cm

GW 50 cm

GW 90 cm

0 N

100 N

0 N

100 N

0 N

100 N

0 N

100 N

Phalaris arundinacea









1992

1.407

1.652

0.325

1.139

0.779

0.693

0.493

0.802

1993

1.812

1.854

0.703

1.566

0.900

1.072

0.670

1.196

1994

1.099

0.984

0.390

0.827

0.547

0.874

0.370

0.684

1995

1.691

1.368

0.870

0.650

0.915

1.516

0.642

1.051

92-95

1.502

1.465

0.572

1046

0.785

1.309

0.544

0.933

Miscanthus sinensis









1992

0.034

0.090

0.079

0.414

1.646

0.378

1.255

1.628

1993

0.021

0.002

0.009

0.023

1.950

0.136

2.807

3.120

1994

0.768

0.108

0.517

0.235

2.601

0.531

2.295

2.226

1995

2.563

0.904

1.856

0.376

1.188

1.872

1.623

2.033

92-95

0.847

0.276

0.615

0.262

1.846

0.729

1.995

2.252

Yields

The results from the lysimeter experiments (given in kg dry matter per m2) showed that Phalaris arundinacea had a high potential yield on moorland. This was due to the high levels of available nitrogen (Table 1). On sand humus gley, Phalaris generally had a lower yield than on low moor.

Miscanthus sinensis returned unacceptably small yields on moor soil. If the plants survived the winter they were, at best, weaker afterwards. Miscanthus grown on sand humus gley produced the highest yields especially at low groundwater levels (90 cm).

Additional experiments were undertaken to investigate the yields of the test species in the field.

On shallow peat soil (Mo lI a2), Miscanthus sinensis showed extremely unfavourable yields. From year to year the population declined and only 52 percent of the crops survived the winter of 1991-1992. The percentage of individuals surviving the winter ranged from 3 076 percent between plots (each 120 m²) and from 0-100 percent between rows (12 m long). In the year 1992 the surviving plants, together with the soil surrounding their root balls, were collected and replanted in smaller plots. In the following winter of 1992-1993, 30 percent of the plants survived. The research was abandoned in 1994.

Phalaris arundinacea was cultivated on moor soil covered with sand.

A yield of 250 dt/ha gross mass or 100 dt/ha dry mass was obtained. Even with very high yields, no problems with storage were encountered and the crop was easy to harvest. In the harvest period from the beginning of July through to August, the average gross mass yield fell from 195 to 151 dt/ha. At the same time the DM content rose from 37.8 to 44.9 percent. Dry mass yield did not change significantly.

As in the lysimeter experiments, Phalaris reacted strongly to nitrogen fertilizers. With the application of 180 kg N ha-1 the theoretical maximum yield was still not obtained. The correlation between nitrogen addition (x kg ha-1) and yield (y dt ha-1) can be represented by the following regression equation:

Y = 36.48 + 0.4434x - 0.0006x2, r2 = 0.924

Thus, with the application of 180 kg N/ha, the production value obtained for the last kg N is still 22.7 kg DM kg N-1.

When harvesting during the growing season, additional expenditure is required to preserve the stored crop. To obtain good quality fuel, DM must be at least 80 percent. This is achievable with a winter harvest (February/March) after a frost period, when the crop has dried. During winter, Miscanthus loses parts of its leaves, whereas Phalaris is still upright and retains its leaves undamaged. Harvesting conditions in winter are difficult, and are only viable when the ground is deeply frozen and therefore able to support the weight of the machinery needed.

REFERENCES

Behrendt, A., Mundel, G. & Holzel, D. (1993). 25 Jahre Paulinenauer Lysimeteranlage eine Zusammenstellung der wichtigsten Forschungsergebnisse. Festschrift des Institutes fur Griinlandand Moorokologie des ZALF Muncheberg, 30 pp. Paulinenaue.

Dingebauer, W. & Meyer, J. (1992). Nachwachsende Rohstoffe fur die Chemie Problem-loser der Zukunft? N. Landwirtsch 4: 35-38, Berlin.

Jacks-Sterrenberg, I. (1995). Wasserhaushalt von Miscanthus sinensis 'Giganteus'. - Mitt. Ges. Pflanzenbauwiss 8: 73-78, Giessen.

Schalitz, G., Scholz, A., Fischer, A. & Kaiser, T. (1996). Function of large-area extensive pasture on shallow undulated low-moor. Proc. 10th Intern. Peat Congress, 2: 184-197, Stuttgart (Schweizerbart).


[15] ZALF Muncheberg, Forschungsstation, Gutshof 7, D-14641 Paulinenaue, Germany
[16] Lehr- and Versuchsanstalt fur Grunland and Futterwirtschaft, Gutshof 7, D-14641 Paulinenaue, Germany
[17] ZALF Muncheberg, Forschungsstation, Gutshof 7, D-14641 Paulinenaue, Germany
[18] Lehr- and Versuchsanstalt fur Grunland and Futterwirtschaft, Gutshof 7, D-14641 Paulinenaue, Germany

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