EVALUASI ASPEK FISIK PRODUKTIVITAS TANAMAN Mk. Stela-smno.fpub.jun2013

EVALUASIASPEK FISIK

PRODUKTIVITAS TANAMAN

Mk. Stela-smno.fpub.jun2013

Pengolahan tanah dapat mempengaruhi panjang akar, meskipung efeknya baru muncul dalam tiga tahun.

Perbedaan porositas tanah dapat diukur pada dua perlakuan pengolahan tanah : Pada tahun pertama ternyata pertumbuhan akar dan infiltrasi air (K sekitar 5 mm/h) sama besarnya pada kondisi olah

tanah minimum dan pengolahan konvensional.

By the third year, when differences were measured between roots, infiltration rates were 84 mm/h in minimum tillage and 0.2 mm/h

under conventional tillage.

Despite the differences in root growth there were no substantial differences in grain yield, reflecting the overall constraint of climate in

the semi-arid environment.

ASPEK FISIK PRODUKTIVITAS TANAMAN

Sumber:http://www.fao.org/docrep/V9926E/v9926e04.htm.

Sumber:.

Values of air-filled porosity (%) and bulk density (g cm3) which are critical and which limit root growth for various soils (Source: Pierce et al. 1983)

1 "Critical" is defined as causing <20% reduction in root growth; "limiting" is about the value at which root growth ceases.

Texture class Non-limiting Critical1 Limiting Air-filled porosity Fine loamy 20 10 5 Coarse silty 20 10 5 Fine silty 20 10 5 Clay:

35-45 15 10 5 >45 15 10 5

Bulk density Sandy 1.60 1.69 1.85 Coarse loamy 1.50 1.63 1.80 Fine loamy 1.46 1.67 1.78 Coarse silty 1.43 1.67 1.79 Fine silty 1.34 1.54 1.65 Claye:

35-45% 1.40 1.49 1.58 45% 1.30 1.39 1.47

Peningkatan kerapatan tanah atau kekuatan tanah dapat menghambat penetrasi akar, sehingga membatasi volume tanah yang dapat

dieksploitasi oleh tanaman dan air tersedia. Biasanya sulit mengkuantifikasikan hubungan antara sifat tanah ini dnegan

pertumbuhan tanaman. In the cases of bulk density and strength, particularly, a gross measure of either for an undisturbed mass of soil

can give only a remote indication of what a root encounters.

A determination of gross bulk density does not assess whether a root is growing within a pore (in which case it may deform surrounding soil

before its radial environment reaches the density or strength of the gross soil) or if it is growing within the soil material, in which case it

has already exerted a radial force equivalent to that measured for the gross soil.



Efek bobot isi tanah dan kekuatan tanah terhadap proses perkecambahan dan pertumbuhan panjang batang juga dipelajari.

Batang (Shoot) mampu memanfaatkan pori makro tanah dengan tidak dibatasi oleh kondisi tanah secara keseluruhan.

Nilai-nilai aktual lokal yg menghambat pemanjangan batang kecambah (shoot) tampaknya sangat kecil, misalnya, 0.76 kPa (Addae and Pearson 1992). Nilai-nilai ini berasal dari kajian pada kondisi yg

terkendali, bebeda dnegan kondisi aktual di lapangan.

The relative ranking of genotypes is, however, the same when under near-critical stress as when growing with virtually no mechanical stress. Genotypes suited to stressful situations may be selected,

therefore, by screening at a single soil strength (Addae and Pearson 1992).



Hubungan antara kekuatan tanah dengan panjang akar relatif tanaman jagung (Kang and Ghuman 1991)


TABLE 11. Grain and stover yield (t/ha) of maize and seasonal water runoff and soil loss under maize grown with and without alley cropping, with two tree legumes, and

tillage in Nigeria (Source: Kang and Ghuman 1991) .1 Seasonal rainfall (March-July 1988) = 704.2 mm.


Treatment Maize Runoff1

(mm [% of rainfall])

Soil loss (t/ha)

grain stover

Without alley cropping

Tilled control 2.3 3.1 66.0 (9.4) 6.18

No-tillage 2.4 3.2 5.6 (0.8) 0.43

Alley-cropped

2 m Gliricidia 3.2 4.6 4.8 (0.7) 0.57

4 m Gliricidia 2.8 4.2 23.1 (3.3) 1.44

2 m Leucaena 3.4 4.9 2.6 (0.4) 9.17

4 m Leucaena 3.1 3.9 10.7 (1.5) 0.82


Tanaman dapat mempengaruhi kualitas tanah melalui ground-cover, kedalaman perakaran, dan sifat-sifat tanaman

lainnya. The crop attributes that most influence soil physical

properties are speed of establishment and development of foliage cover.

Rapid establishment and growth minimizes topsoil structural decline and soil erosion by wind and water.

Thereafter, deep-rooting directly affects soil structure, particularly if deep-rooted crops, such as safflower, are grown in rotation as a

'biological plough' to create macropores and these are minimally disturbed before the next crop is sown.



Sumber:.

TABLE 12. Desirable crop attributes that sustain soil productivity ASPEK FISIK PRODUKTIVITAS TANAMAN

Attribute Contributing characteristicRapid establishment (Relatively) large seed for establishment and seedling vigour;

abundant seed for propagationGroundcover to reduce soil exposure, suppress weeds

Early branching; perhaps rhizomes or stolons; horizontal leaves (high canopy-extraction coefficient)

Low requirements for nutrients · Colonization by associative bacteria (e.g., Brachyrhizobiun), micorrhizae (e.g., Glomus) and free-living organisms (e.g., Azospirillum)· Low P, K, etc. requirement per unit dry matter, e.g., high "phosphate efficiency"

Efficient water use Short growth duration (to utilize residual moisture after crop); high water use efficiency

Deep rooting to reduce water table (salinity) and recover nutrients at depth and increase macropores

Vertical root distribution; roots penetrate high impedence soils

Useful products High leaf/stem ratio; edible seeds; easily digestible; no nutritional compounds in material for livestock; leaf retention on stems for cut and carrying to livestock

Non-host for diseases and pests of main crop (to break disease cycle) or decoy (to attract diseases from concurrent crops)

Botanically unrelated to main food crop(s)

Suppress other species Allelopathy (leachates, exudates which suppress or kill other plant species); also physical attributes (as above)

Indikator Lapangan problematik Fisika-tanah

Indikator lapangan yang lazim bagi kondisi fisika tanah yang buruk adalah:

1. Patchiness or absence of vegetation. This can be an obvious sign of degraded structure or other factors. When structural, it may reflect surface structure degradation (see previous sections) or non-wetting characteristics which give rise to poor infiltration, or subsoil impermeability.

2. Vegetasi bergulma. Cyperaceae atau Juncaceae dapat mencerminkan jeleknya struktur tanah, karena mereka tumbuh subur kalau air tergenang di permukaan tanah, menunjukkan jeleknya laju infiltrasi atau adanya lapisan bawah yang kedap air.



Indikator Lapangan problematik Fisika-tanah


3. Erosi permukaan dan erosi alur. Erosive runoff may be symptomatic of poor surface structure. The turbidity of water in ponds and lakes after rain may be a good indicator of erosion.

4. Kerak tanah di permukaan. 5. Permukaan tanah yang mengeras. 6. Infiltrasi yang jelek dan genangan air. This may be indicated by

puddles following rain in an area where one would expect rapid infiltration, or by wetting to only a shallow depth (as seen when dug with a spade).




7. Warna tanah permukaan pucat dan tidak ada bahan organik. The surface of degraded soils may be brittle and pale, lacking organic matter and having lost clay either through eluviation (differential movement downwards) or by water or wind erosion.

8. Berbongkah-bongkah (Cloddiness). This may be apparent if after a single cultivation, large, tough clods are formed requiring further cultivation to form a reasonable seedbed.




9. Peetumbhuhan akar terhambat. This can be seen by digging with a narrow-faced spade and washing the roots free of soil. The root mass can be restricted to the upper soil or be constricted in particular places such as a less pervious layer, above and below which the roots may proliferate.



TABLE 16. Examples of farmer concepts/statements concerning aspects of sustainable crop production (Source:

Fujisaka and Garrity 1991)

Tanaman dan Hara dalam tanah

1. Ubikayu dapat mengasamkan tanah.2. Ubikayu “menguras” hara dari tanah.3. Padi lebih toleran tanah-tanah masam dibandingkan

Jagung.4. Rice is more vigourous on an area previously planted

in tomato.5. Intercropping bagus kalau ketersediaan haranya

cukup


Pengurasan Hara Tanah:

1. Kesuburan tanah telah digunakan oleh tanaman.2. Tanah menjadi lemah.3. Fertility is spotty.4. Soils are overtrained.5. Tanah-tanah menjadi semakin lebih tua.6. Poor, but not used up, in the sense of the hardest

part within a log.


Contoh Konsep/Pendapat Petani tentang aspek-aspek Produksi Tanaman Berkelanjutan (Fujisaka and Garrity 1991)

Contoh Konsep/Pendapat Petani tentang aspek-aspek Produksi Tanaman Berkelanjutan (Fujisaka and Garrity 1991)

Lahan bero (kosong) - Fallows:

1. Biomasa gulma yg terdekomposisi membantu memperkaya tanah.

2. Lahan istirahat sehingga tanah dapat menyimpan sejumlah hara.

3. Kaya karena beristirahat.4. Fertility is added and the soil is made cool.5. The soil is slightly enriched if left a short time.


TABLE 16. Examples of farmer concepts/statements concerning aspects of sustainable crop production (Source: Fujisaka and

Garrity 1991)

Gulma - Weeds1. Padi dirugikan oleh akar-akar cogon (I. cylindrical).2. Tanah menjadi jelek kalau cogon dominan.3. D. longiflora and cogon consume soil nutrients and destroy soil

quality.4. Kemasmaan tanah meningkat kalau cogon dominan.5. Gula kurus pada tanah-tanah tidak subur.6. R. cochinchinensis rapidly produces seed; thus, easily soars in

population; if not weeded, it exceeds the height of rice or corn.7. Fertility is added and the soil is made cool" (re. Calapogonium

spp.).8. Tanah menjadi baik kalau ada gulmua/rumput mempunyai bintil

akar.


TABLE 16. Examples of farmer concepts/statements concerning aspects of sustainable crop production (Source:


Erosi Tanah:1. Tanah terkikis dan terangkut ke tempat lain.2. Hara terangkut.3. Tumbuhan tererosi bersama dnegan tanahnya.4. Soil was drawn down and fertility was washed out.5. The land was shaven and eroded after trees were

removed.6. Pupuk terkumpul (di bagian bawah petakan) karena

terbawa air hujan.


Tabel 16. Examples of farmer concepts/statements concerning aspects of sustainable crop production (Source:


Kontrol Erosion :1. Pisang dan Kelapa lebih baik karena mereka mampu

menahan tanah.2. Pengolahan menurut kontur mengurangi kehilangan

erosi.3. Jalur-jalur rumput dapat mengurangi efek erosi4. Trees planted above and below fields can decrease

erosion effects.5. Banana planted above and below fields can decrease

erosion effects.Sumber:http://www.fao.org/docrep/V9926E/v9926e04.htm.

EVALUASI ASPEK FISIK PRODUKTIVITAS TANAMAN Mk. Stela-smno.fpub.jun2013

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