Bahan kajian
Dasar-dasar
PENGELOLAAN
KESUBURAN TANAH
Oleh:
Prof.Dr.Ir.Soemarno,M.S.
Jur. Tanah FP-UB, September 2011
LIMA
Pengendalian GULMA
.
FAKTOR
PENGELOLAAN
TANAH
PERGILIRAN TANAMAN
PENGENDALIAN HAMA & PENYAKIT
PENYEDIAAN UNSUR HARA
Penyediaan AIR YANG CUKUP
DINAMIKA
HARA TANAH
Mempertahankan jumlah optimum unsur hara
hanya dapat terlaksana dengan menciptakan
keseimbangan yang baik antara penambahan dan
kehilangannya
Benefits of Organic Matter
Reduces compaction and bulk density
Provides a food source for microorganisms
Increases activities of earthworms and other soil
critters
Benefits of Organic Matter
Increases soil CEC
Stabilizes nutrients
Builds soil friability and tilth
Reduces soil splash
Carbon Sequestration
C cycling in agroecosystems has a significant impact at the global scale because
agriculture occupies approximately 11% of the land surface area of the earth.
POKOK-POKOK
PENGELOLAAN
KESUBURAN
TANAH.
1. Suplai nitrogen dari:
Sisa Tanaman
Pupuk kandang
Hujan & irigasi
Pupuk nitrogen
2. Penambahan bahan organik melalui:
Sisa tanaman legume dan non legume
Pupuk kandang
Pupuk hijau
4. Penambahan fosfat:
Pupuk superfosfat, atau
Pupuk lainnya
6. Kekurangan belerang diatasi dg:
Belerang,
gipsum,
superfosfat,
Amonium
sulfat,
Senyawa
belerangdalam air hujan
Tanaman biasa
Tanaman legume
Pupuk hijau
Kompos
3. Penambahan kapur bila diperlukan
Batu kapur kalsit atau dolomit yg
biasa dilakukan
5. Penambahan kalium tersedia:
Pupuk kandang
Sisa tanaman
Pupuk Kalium
7. Penambahan unsur mikro: Sebagai
garam terpisah atau campuran
MENGATASI
KEKURANGAN
NITROGEN
Ketersediaan nitrogen dalam tanah sangat dipengaruhi oleh
keberadaan bahan organik dalam tanah
Apa saja yang dapat dilakukan untuk itu?.......
Penambahan & Kehilangan N-tersedia
Pengikatan Nitrogen
Simbiotik
Pupuk
Buatan
Non-Simbiotik
Sisa tanaman
Pupuk Kandang
N-tersedia
dlm tanah
Atmosfer
Bahan Organik
Panen
Tanaman
Hilang
Pencucian
Hilang
Erosi
MEMPERTAHANKAN
BAHAN ORGANIK
TANAH
Carbon Inputs to Soil
Crop residues
Cover crops
Compost , and Manures
Carbon Substrate
The majority of C enters the soil in the form of complex organic matter containing
highly reduced, polymeric substances.
During decomposition, energy is obtained from oxidation of the C-H bonds in the
organic material.
Soil Carbon Equilibrium
Input primarily as plant products
Output mediated by activity of decomposers
It is common that from 40 to 60% of the C taken up by microorganisms is
immediately released as CO2.
PENTINGNYA
Ca & Mg
Ketersediaan Ca dan Mg dalam tanah biasanya ditentukan
oleh bahan induk tanah.
Kapur pertanian merupakan sumber Ca dan Mg yang
lazim digunakan ke tanah-tanah masam yang defisien Ca
dan Mg
Penambahan dan kehilangan
Sisa tanaman &
Pupuk Kandang
Pupuk Komersial
Ca dan Mg tersedia
dalam tanah
PANEN
TANAMAN
Hilang pencucian
Mineral Tanah
KAPUR
Hilang Erosi
Ketersediaan fosfat dalam tanah ternyata berkaitan erat
dengan fenomena fiksasi fosfat oleh partikel-partikel tanah
dan pH tanah.
…………. Bagaimaan optimasinya? ..
MEMPERTAHANKAN
KETERSEDIAAN
FOSFAT.
Kehilangan & Penambahan P-tersedia
Sisa tanaman
Pukuk kandang
Bahan
Organik
Tanah
Terangkut
tanaman
Pupuk komersial
Mineral P-tanah
P-tersedia dalam tanah
Hilang
Pencucian
Hilang Erosi
Fiksasi
KETERSEDIAAN
KALIUM
Tanah mineral umumnya mengandung cukup banyak
kalium, kisaran 40 ton setiap hektar lapisan olah tanah.
Namun demikian hanya sebagian kecil yangtersedia bagi
tanaman
Kehilangan & Penambahan Kalium:
Sisa tanaman &
Pupuk Kandang
Pupuk komersial
Mineral-K
lambat tersedia
K-tersedia tanah
Terangkut tanaman
Kehilangan
pencucian
Kehilangan
erosi
Kehilangan
Fiksasi
The Soil Food Web
In 1 teaspoon of soil there are…
5 or more ------------ Earthworms
Up to 100 ……………. Arthropods
10 to 20 bacterial feeders and a few fungal feeders ……. Nematodes
Several thousand flagellates & amoeba
One to several hundred ciliates ……. Protozoa
6-9 ft fungal strands put end to end ………. Fungi
100 million to 1 billion …………. Bacteria
Classical C Pools
Nonhumic substances—carbohydrates, lipids,
proteins
Humic substances—humic acid, fulvic acid, humin
BOT berpengaruh terhadap:
-Plant nutrition
-Soil and Plant health
-Soil physical, chemical and biological
properties
11
BOT ----- FRAKSI RINGAN
The light fraction (LF) with a density of ~1.6 gm cm-3 is
relatively mineral free and consists of partially decomposed
plant material, fine roots and microbial biomass with a rapid
turnover time.
The LF is a source of readily mineralizable C and N, accounts
for ~50% of total soil C and declines rapidly under
cultivation.
12
BOT --- FRAKSI BERAT --- The Heavy Fraction
The heavy fraction (HF) is organic matter adsorbed
onto mineral surfaces and sequestered within
organomineral aggregates.
The HF is less sensitive to disturbance an chemically
more resistant than the LF.
13
Major features of some representative soil
bacteria (true bacteria).
Bacteria vs. Fungi
Bacteria are smaller than fungi
and can occupy smaller pores
and thus potentially have
greater access to material
contained within these pores.
Bacteria are less disrupted
than are fungi by tillage
practices commonly used in
agriculture.
Sumber: http://filebox.vt.edu/users/chagedor/biol_4684/Microbes/SoilBiota.html
14
Bacteria vs. Fungi
Fungi tend to be selected for by plant residues with
high C/N ratios.
Fungi have a greater influence on decomposition in
no-till systems in which surface residues select for
organisms that can withstand low water potentials
and obtain nutrients from the underlying soil profile.
15
Bacteria vs. Fungi
Fungi often produce more cell wall than cytoplasmic
material when starved for N, and thus can extend
into new regions of the soil without requiring
balanced growth conditions.
The filamentous growth structure of a fungus
permits it to access C in one location and nutrients in
another.
16
Soil Organic Matter Content
How organic matter in soil influences the soil-plant
relationship?
• Decomposed organic matter provides nutrients for plant
growth (Mineralization)
• It determines the soil’s temperature, air ventilation,
structure and water management
• It contains bioregulators which affects plant growth
• It contains bioregulators, which affects plant growth
(enzymes, hormones, etc.)
• Its carbon and energy content is the soil’s energy battery
for future use
• It determines the soil’s capacity to compensating,
regenerating and protecting the environment
regenerating and protecting the environment
17
PENTINGNYA BOT
➢ Organic material in the soil is essentially derived from
residual plant and animal material, synthesised by microbes
and decomposed under influence of temperature, moisture
and ambient soil conditions
➢ Soil organic matter is extremely important in all soil
processes
➢ Cultivation can have a significant effect on the organic
matter content of the soil
➢ In essentially warm and dry areas like Southern Europe,
depletion of organic matter can be rapid because the
processes of decomposition are accelerated at high
temperatures
➢ Generally, plant roots are not sufficiently numerous to
replace the organic matter that is lost
18
MANFAAT BOT
➢ Storehouse for nutrients
➢ Source of fertility
➢ Contributes to soil aeration thereby reducing soil
compaction
➢ Important ‘building block’ for the soil structure
➢ Aids formation of stable aggregates
➢ Improves infiltration/permability
➢ Increase in storage capacity for water.
➢ Buffer against rapid changes in soil reaction (pH)
➢ Acts as an energy source for soil micro-organisms
19
Degradation: HILANGNYA BOT
➢ During field operations, fresh topsoil becomes exposed
and dries rapidly on the surface
➢ Organic compounds are released to the atmosphere
result from breakdown of soil aggregates bound together
by humic materials
➢ Unless the organic matter is quickly replenished,
the system is in a state of degradation leading
eventually to un-sustainability
➢ The removal of crop residues in dry ecosystems,
which are inherently marginal, can cause such systems
to be quickly transformed from a stage of fragility to
total exhaustion and depletion
20
FAKTOR YG PENGARUHI BOT
Natural factors:
➢ Climate
➢ Soil parent material: acid or alkaline (or even saline)
➢ Land cover and or vegetation type
➢ Topography – slope and aspect
Human-induced factors:
➢Land use and farming systems
➢Land management (cultivation)
➢Land degradation
21
FAKTOR IKLIM PENGARUHI BOT:
Temperature:
OM decomposition rapid in warm climates
OM Decomposition is slower for cool regions
Result:
Within zones of uniform moisture and comparable vegetation -Av total OM increases 2x to 3x for each 10 deg C fall in mean
temperature
Moisture:
OM decomposition rapid in warm climates
OM Decomposition is slower for cool regions
Result:
Under comparable conditions
Av total OM increases as the effective moisture increases
22
Sumber:
pgsgrow.com/blog/tag/organicgardening/
Dalam tanah terdapat beragam
organisme tanah yang berperan
sangat penting dalam
menentukan kualitas kesuburan
tanah
Sebagian dari mikroba tanah ini
berperan dalam dekomposisi
bahan organik dalam tanah dan
melepaskan hara mineral dalam
bentuk tersedia bagi tanaman
23
Structure of soil, indicating presence of bacteria, inorganic, and
organic matter
Sumber: www.cartage.org.lb/en/themes/sci...ones.htm
24
INTEGRATED SOIL FERTILITY MANAGEMENT
Integrated soil fertility management (ISFM) aims at the optimal
and sustainable use of soil nutrient reserves, mineral fertilizers and
organic amendments. We explain in this reference how to calculate
mineral and organic fertilizer needs to obtain target yields as a
function of the soil nutrient.supplying capacity (mainly nitrogen, N;
phosphorus, P; potassium, K) and taking into account yield potential
(determined by cultivar choice, sowing date and climate). Analysis of
soil fertility using laboratory procedures is seldom possible in
farmers' fields, and the relation between such analyses and rice
growth is often poor, especially for nitrogen. This reference offers
another method to determine the soil nutrient-supplying capacity. The
rice yield from a mini-plot, with good soil.fertility management but
without application of one nutrient (for instance, without N, P or K)
is considered as an indicator of the capacity of the soil to supply that
Imissing nutrient.
INTEGRATED SOIL FERTILITY MANAGEMENT
To increase yield by 1 t / ha, nutrient uptake at maturity needs to
increase by 15 kg N / ha, 6 kg P2O5/ha and 18 kg K2O / ha. A
well.balanced fertilization thus requires an application of 50 kg N /
ha, 30 kg P2O5/ha and 60 kg K2O / ha to increase yield by 1 t / ha,
based on a recovery rate of applied fertilizer of 30% for N and K and
of 20% for P. The recovery rate is the percentage of fertilizer
effectively absorbed by the plant as compared to the quantity applied.
These relations are approximate and only valid for yields not
exceeding 70 to 80% of the potential yield. For higher yield targets,
more nutrients have to be applied to get the same return, and this is
not usually cost.effective. Nitrogen losses are irreversible, thus it is
very important to increase the recovery rate of this nutrient. The
recovery rate of nitrogen is strongly related to crop management.
INTEGRATED SOIL FERTILITY MANAGEMENT
This reference provides instructions to help increase this recovery
rate. For P and K, losses are much less (P and K are absorbed by the
soil), and the residual effect of the fertilizer applied is often visible
several years after application. Organic fertilizer can, to a certain
extent, replace mineral fertilizers, but large quantities need to be
applied as organic fertilizers have a low nutrient content. However,
using both mineral fertilizers and organic amendments often has
synergistic effects, increasing the soil's nutrient.supplying capacity in
the long term and in some cases increasing the recovery rate of
mineral fertilizer nutrients.
SITE SPECIFIC INTEGRATED SOIL FERTILITY
MANAGEMENT
Integrated soil-fertility management aims at the optimal and
sustainable use of nutrient stocks from the soil, mineral fertilizers and
organic amendments. A procedure is given below for calculating
fertilizer needs to reach target yields as a function of the soil
nutrientYsupplying capacity and potential yield.
Three steps are necessary:
Fix a target yield.
Estimate the capacity of the soil to supply N, P and K.
Calculate fertilizer requirements.
A number of good crop management practices help limit losses of
N applied with mineral fertilizers:
1. Using good-quality seed.
2. Transplanting seedlings at the right age.
3. Using a plant spacing that is adequate for the variety used,
usually 0.2 × 0.2 m.
4. Removing weeds before fertilizer application.
5. Using pest and disease control.
6. Harvesting on time, at maturity.
7. Applying N when the crop most needs it: at tillering, panicle
initiation and, if required, at heading; for small N doses, apply at
tillering and panicle initiation.
8. Using N in two splits of 50% each, at the start of tillering and at
panicle initiation, or in three splits of 40%, 40% and 20%,
respectively, at the start of tillering, at panicle initiation and at
heading.
MODEL NEPALESE:
Integrated plant nutrient components in the farming system
FAO. Paper Number 3. Plant nutrient management for improving crop productivity
in Nepal. D.P. Sherchan and K.B. Karki.
http://www.fao.org/docrep/010/ag120e/AG120E10.htm
MODEL NEPALESE:
Nutrient flow components in the Nepalese farming system
FAO. Paper Number 3. Plant nutrient management for improving crop productivity in Nepal.
D.P. Sherchan and K.B. Karki. http://www.fao.org/docrep/010/ag120e/AG120E10.htm
Model of soil-plant transfer of mineral
nutrients
Modelling nutrient uptake by crops implies considering
and integrating the processes controlling the soil nutrient
supply, the uptake by the root system and relationships
between the crop growth response and the amount of
nutrient absorbed. We have developed a model that
integrates both dynamics of maize growth and phosphorus
(P) uptake. The crop part of the model was derived from
Monteith's model.
A complete regulation of P-uptake by the roots according
to crop P-demand and soil P-supply was assumed. The soil
P-supply to the roots was calculated using a diffusion
equation and assuming that roots behave as zero sinks. The
actual P-uptake and crop growth were calculated at each
time step by comparing phosphate and carbohydrate
supply-demand ratios. Model calculations for P-uptake and
crop growth were compared to field measurements on a
long term P-fertilization trial.
http://www.bordeauxaquitaine.inra.fr/tcem_eng/recherche/nutrition_minerale_et_gestio
n_de_la_fertilite
Biogeochemical cycle of mineral
nutrients in agricultural
ecosystems
The objective is to develop new
approaches to the measurement and
understanding of the behaviour of P
cycling in agricultural ecosystems. This
includes both to analyze and quantify
inputs and outputs of P at the field
scale for different cropping systems
and also to assess associated P
transformations in soils. We mainly
focuse our research on the soil P
availability to plants in agricultural
soils because available soil P often
control the greatest annual P flux that
affect P cycling. We develop a processbased assessment of plant-available
soil P which accounted for
orthophosphate ions in solution and the
amount of P ions associated to soil
constituents that can diffuse with time
towards solution.
http://www.bordeaux-aquitaine.inra.fr/tcem_eng/recherche/nutrition_minerale_et_gestion_de_la_fertilite
Terima kasih
semoga manfaat
Wss.